Biomedical subjects

S Mao

Publications and source records attributed to S Mao.

At least 37 records · Page 2Linked to original sources

PubMed2000

Rates of progression of coronary calcium by electron beam tomography.

In this study, we sought to determine the rate of progression of atherosclerosis using coronary calcium scores derived from electron beam tomography (EBT). We studied a variety of disease states (hypertension, high cholesterol, tobacco use, diabetes mellitus) followed for 1 to 6.5 years. We evaluated 299 asymptomatic persons (227 men and 72 women) who underwent 2 consecutive EBT scans at least 12 months apart. The average change in the calcium score (Agatston method) for the entire group was 33.2 +/- 9.2%/year. The treated group (receiving statins) demonstrated an average increase in calcium scores of 15 +/- 8%/year compared with 39 +/- 12%/year for untreated patients (p <0.001). Among the 60 patients on statin monotherapy, 37% had a decrease in the calcium score from baseline to follow-up scan. The relative increase in calcium scores did not vary significantly by gender or risk factors, with the exception of statin-treated hypercholesterolemic subjects. Scores of zero on the initial scan portend a low likelihood of significant calcific deposits on repeat scanning. Only 2 of 81 participants (2%) with scores of zero at baseline had scores >10 on repeat study. In this study, statin therapy induced a 61% reduction in the rate of coronary calcium progression. This study demonstrates that EBT may be a useful tool in assessing efficacy of different interventions to retard progression of atherosclerosis, noninvasively, over relatively short time periods.

Adult↗

PubMed2000

Preview method for electron-beam CT scanning of the coronary arteries.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks. MATERIALS AND METHODS: Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared. RESULTS: All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found. CONCLUSION: The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.

Coronary Angiography↗

PubMed2000

A simple single slice method for measurement of left and right ventricular enlargement by electron beam tomography.

RATIONALE AND OBJECTIVE: We devised to test the feasibility of measuring the left and right ventricular sizes by non-contrast electron beam tomographic images. METHODS: Ventricular sizes consist of the sum of the intracavitary cavity and myocardial mass for each ventricle. A total of 50-image studies from subjects undergoing contrast-enhanced studies were used to develop the measurement methodology. About 20 contrast studies were used to test the measure. The methodology was then prospectively tested on 75 patients with non-contrast studies to estimate the intra-observer, inter-observer and inter-study reproducibility. RESULTS: Multiple linear regression analysis was completed and the correct regression formulas to calculate ventricular volumes were acquired by using the area and span from the contrast studies. There was excellent correlation between the estimate of LV (r > 0.97, p < 0.001) and RV (r > 0.93, p < 0.001) sizes between measured and calculated (contrast, single slice) left and right ventricular volumes. The intra-observer, inter-observer and inter-study reproducibility demonstrated excellent results with < 7% difference in absolute values and a high correlation (r > 0.89, p < 0.001). CONCLUSION: We conclude that the left and right ventricular sizes can be accurately estimated from a single mid-ventricular slice on non-contrast electron beam tomographic images.

Case-Control Studies↗

PubMed2000

Mitochondrial transcription factor A is increased but expression of ATP synthase beta subunit and medium-chain acyl-CoA dehydrogenase genes are decreased in hearts of copper-deficient rats.

The mechanism(s) by which impaired mitochondrial respiratory function and the accumulation of lipid droplets and mitochondria in hearts of copper-deficient rats occur remains unclear. It is not known whether specific components of the regulatory pathway involved in mitochondrial biogenesis, such as mitochondrial transcription factor A (mtTFA) and nuclear respiratory factors 1 and 2 (NRF-1 and NRF-2), are activated in copper deficiency. Little is known about gene expression of enzymes involved in fatty acid oxidation (FAO) in hearts of copper-deficient rats. Male weanling rats were fed copper-adequate (CuA), copper-deficient (CuD) or pair-fed (CuP) diets for 5 wk. Mitochondria and lipid droplet volume densities from electron micrographs were greater and there was an elevation in the mtTFA protein level in hearts of copper-deficient rats. DNA binding activities of NRF-1 and NRF-2 did not differ among the groups. Northern blot analysis of cardiac tissue revealed that transcripts of F(1)F(0)-ATP synthase subunit c were greater, but mRNA levels of ATP synthase beta subunit and the FAO enzyme, medium-chain acyl-CoA dehydrogenase (MCAD), were lower in hearts of copper-deficient rats. Long-chain acyl-CoA dehydrogenase (LCAD) mRNA levels did not differ among treatment groups. These results suggest that certain components of the mitochondrial biogenesis program are activated in hearts of copper-deficient rats. F(1)F(0)-ATP synthase beta subunit and MCAD transcript levels remain low, which may contribute to impaired mitochondrial respiratory function, decreased fatty acid utilization and lipid droplet accumulation in hearts of copper-deficient rats.

Acyl-CoA Dehydrogenase↗

PubMed2000

Evaluation of fluid collection in the pericardial sinuses and recesses: noncontrast-enhanced electron beam tomography.

RATIONALE AND OBJECTIVES: To evaluate the attenuation, size, and volume of the pericardial sinuses and recesses by using electrocardiographically triggered, noncontrast-enhanced electron beam tomography (EBT) and to consider its relation with sex, age, and heart volume. METHODS: Findings in 213 consecutive patients without known pericardial disease were studied. The patients underwent EBT scanning of the heart to evaluate coronary artery calcification. Incremental electrocardiographically triggered noncontrast images were obtained with a 100-ms exposure time and a 3-mm slice thickness. The appearance, density, and volume of the pericardial sinuses and recesses were calculated. RESULTS: Among the 213 patients, 97.2% had at least one of the sinuses or recesses visible on EBT. The sinuses or recesses were seen with the following frequency: transverse sinus (93.9%), oblique sinus (71.8%), and superior aortic recess (51.2%). The mean attenuation and volume were 9.9 +/- 7.3 Hounsfield units (HU), 12.6 +/- 8.1 HU, and 12.6 +/- 8.7 HU, and 1.9 +/- 1.3 mL, 1.3 +/- 1.0 mL, and 0.8 +/- 0.8 mL, respectively. The total volume of the pericardial sinuses (3.3 +/- 2.2 mL) had no significant relation with the total heart volume. CONCLUSIONS: Pericardial sinuses and recesses were frequently and well depicted on noncontrast EBT images. In patients without obvious pericardial effusion, physiological fluid collections were observed in the transverse and oblique sinuses or other recesses. Location, attenuation, and volume were helpful in the differentiation of normal pericardial sinuses from pericardial effusions and mediastinal lymph nodes.

Adult↗

PubMed2000

[Relationship between estrogen receptor and Graves' disease].

OBJECTIVE: To study the relation of expression of estrogen receptor (ER) in thyroid tissues with Graves' disease (GD). METHODS: ER was detected in the tissues of 40 patients with GD and 15 patients with normal thyroid by immunohistochemical method. Gene expression of ER was studied in frozen slides of 26 GD thyroids and 10 normal thyroids by fluorescence in situ hybridization (FISH) together with image analysis system. RESULTS: In immunohistochemical detection, the positive rate of ER in GD group was 70% (28/40), but 13.3% (2/15) in the control group (P < 0.01). The positive degree of ER in female with GD was higher than that in male with GD (P < 0.05). The positive rate of ER in the female GD group below 35 years was 85.0% (17/20) and 50% (5/10) in the female GD group above 35 years (P < 0.05). In FISH, the optical density (A) value of the female GD group was 30.14 +/- 10.74, and in the male GD group 21.06 +/- 7.71, but in the control group it was 16.91 +/- 5.30 (P < 0.01). The A value of the female GD group below 35 years was 33.85 +/- 10.10, and 23.24 +/- 7.48 in the female GD group above 35 years (P < 0.05). CONCLUSIONS: The increasing of ER content is related to the development of GD. Estrogen may be a promoting factor for GD. The sex and age differences in GD development are associated with the effects of estrogen and ER.

Adult↗

PubMed1999

Effect of exercise on left and right ventricular ejection fraction and wall motion.

OBJECTIVE: We evaluated the diagnostic value of response of left and right ventricular ejection fraction and wall motion to exercise using electron beam computed tomography. METHODS AND RESULTS: We attempted to determine the value of exercise electron beam computed tomography for detecting coronary artery disease, including evaluation of the right ventricular ejection fraction and wall motion abnormalities. A study of 35 patients undergoing electron beam tomography exercise cine studies and coronary artery angiography for the evaluation of chest pain was performed. Of the 18 patients with significant coronary disease (> or = 50% luminal diameter stenosis in at least one coronary artery), 17 (94%) had failure to increase global left ventricular ejection fraction with exercise. Fourteen of 18 (78%) developed a wall motion abnormality during peak exercise, and eight (44%) developed a regional right ventricular wall motion abnormality during peak exercise. Of the 17 patients without obstructive disease, 14 (82%) had a increase in ejection fraction > or = 5% and none had an abnormal response in left ventricular wall motion during peak exercise (specificity = 100%). The change in right ventricular ejection fraction with exercise was not a significant predictor of obstructive coronary disease in this study (P=NS). Using different criteria during stress to predict coronary disease, the accuracy was 89% (31/35) using an increase of <5% in ejection fraction, 89% (31/35) using the development of a new or worsened wall motion abnormality, and 91% (32/35) using both left ventricular criteria. CONCLUSION: Our study suggests that exercise electron beam computed tomography appears to be a useful tool for the detection of coronary disease. A increase of <5% in ejection fraction and abnormal left ventricular response to exercise were important predictors, while the exercise induced changes of right ventricular ejection fraction was not a significant predictor of obstructive disease. Both left and right ventricular wall motion abnormalities are useful and important parameters in identifying patients with obstructive disease from those with normal coronary arteries.

Adult↗

PubMed1999

Phage-display library selection of high-affinity human single-chain antibodies to tumor-associated carbohydrate antigens sialyl Lewisx and Lewisx.

mAbs against tumor-associated carbohydrate antigens have the potential to play a prominent role in cancer immunotherapy. However, it has not been possible to fully exploit the clinical utility of such antibodies primarily, because those of adequate affinity could be derived only from murine sources. To address this problem, we prepared a single-chain Fv (scFv) antibody library from the peripheral blood lymphocytes of 20 patients with various cancer diseases. Completely human high-affinity scFv antibodies were then selected by using synthetic sialyl Lewisx and Lewisx BSA conjugates. These human scFv antibodies were specific for sialyl Lewisx and Lewisx, as demonstrated by ELISA, BIAcore, and flow cytometry binding to the cell surface of pancreatic adenocarcinoma cells. Nucleotide sequencing revealed that at least four unique scFv genes were obtained. The Kd values ranged from 1.1 to 6.2 x 10(-7) M that were comparable to the affinities of mAbs derived from the secondary immune response. These antibodies could be valuable reagents for probing the structure and function of carbohydrate antigens and in the treatment of human tumor diseases.

Amino Acid Sequence↗

PubMed1999

Making artificial antibodies: a format for phage display of combinatorial heterodimeric arrays.

The gene VII protein (pVII) and gene IX protein (pIX) are associated closely on the surface of filamentous bacteriophage that is opposite of the end harboring the widely exploited pIII protein. We developed a phagemid format wherein antibody heavy- and light-chain variable regions were fused to the amino termini of pVII and pIX, respectively. Significantly, the fusion proteins interacted to form a functional Fv-binding domain on the phage surface. Our approach will be applicable to the display of generic peptide and protein libraries that can form combinatorial heterodimeric arrays. Consequently, it represents a first step toward artificial antibodies and the selection of novel biological activities.

Amino Acid Sequence↗

PubMed1999

Simple single-section method for measurement of left and right atrial volumes with electron-beam CT.

RATIONALE AND OBJECTIVES: The authors estimated left and right atrial volumes by using a simple method of measurement with nonenhanced electron-beam computed tomography (CT). MATERIALS AND METHODS: One hundred sixty-four contrast material-enhanced electron-beam CT studies were divided into two groups. Group 1, which included 104 studies, was used to develop the measurement method (i.e., the formulas) for measuring left and right atrial volumes from a nonenhanced study. Group 2 consisted of 60 studies on which the validity of the method was tested. Measurement of left and right atrial volumes was performed on all section levels by tracing the respective atrial borders for each section, then multiplying the area by section thickness and summing the resultant volumes. RESULTS: Calculated left and right atrial volumes were derived by using the biggest atrial area and cephalic-caudal span. The span was equal to section thickness times the number of sections in which the atria were present. Linear regression analysis formulas were acquired with the biggest atrial area and cephalic-caudal span. Left and right atrial calculated volumes were obtained with these formulas and demonstrated a significant good relation (r > .95, P < .001) and a difference of less than 11% (P < .05) in absolute values between measured and calculated volumes. Intraobserver, interobserver, and interstudy reproducibility were excellent, with less than 10% difference in absolute values. CONCLUSION: Left and right atrial volumes can be accurately estimated from a single midventricular section by using nonenhanced electron-beam CT.

Anatomy, Cross-Sectional↗

PubMed1999

Functional and physical interactions between AML1 proteins and an ETS protein, MEF: implications for the pathogenesis of t(8;21)-positive leukemias.

The AML1 and ETS families of transcription factors play critical roles in hematopoiesis; AML1, and its non-DNA-binding heterodimer partner CBFbeta, are essential for the development of definitive hematopoiesis in mice, whereas the absence of certain ETS proteins creates specific defects in lymphopoiesis or myelopoiesis. The promoter activities of numerous genes expressed in hematopoietic cells are regulated by AML1 proteins or ETS proteins. MEF (for myeloid ELF-1-like factor) is a recently cloned ETS family member that, like AML1B, can strongly transactivate several of these promoters, which led us to examine whether MEF functionally or physically interacts with AML1 proteins. In this study, we demonstrate direct interactions between MEF and AML1 proteins, including the AML1/ETO fusion protein, in t(8;21)-positive acute myeloid leukemia (AML) cells. Using mutational analysis, we identified a novel ETS-interacting subdomain (EID) in the C-terminal portion of the Runt homology domain (RHD) in AML1 proteins and determined that the N-terminal region of MEF was responsible for its interaction with AML1. MEF and AML1B synergistically transactivated an interleukin 3 promoter reporter gene construct, yet the activating activity of MEF was abolished when MEF was coexpressed with AML1/ETO. The repression by AML1/ETO was independent of DNA binding but depended on its ability to interact with MEF, suggesting that AML1/ETO can repress genes not normally regulated by AML1 via protein-protein interactions. Interference with MEF function by AML1/ETO may lead to dysregulation of genes important for myeloid differentiation, thereby contributing to the pathogenesis of t(8;21) AML.

Amino Acid Sequence↗

PubMed1999

[Experimental study on effect of guyubao in promoting the fracture healing in kidney deficiency rabbits].

OBJECTIVE: To study the effect of Guyubao (GYB) in promoting the fracture healing of Kidney deficiency (KD) rabbits. METHODS: Fifty-seven rabbits were randomly divided into three groups: The blank group (A), the control group (B) and the experimental group (C). After the periosteum was peeled off, 0.73 cm middle section defects on both radius were removed. One week after operation, the experiment was begun: Group A was fed normally; group B fed normally plus 6 mg/(kg.d) prednisolone; group C fed with food mixed with GYB and 6 mg/(kg.d) prednisolone. The general state and body weight were observed. The rabbits were sacrificed at three and six weeks after the beginning of experiment. Both radius were observed with X-ray and histologic examination. RESULTS: In group A, no KD appeared, group B gradually developed KD, and mild KD appeared in group C but adjusted rapidly. The healing of radial defect in order were C, A, B from higher to lower degree. CONCLUSION: The results revealed that the GYB could correct the KD and promote fracture healing.

Animals↗

PubMed1999

[Studies on chemical constituents of the stem bark of Taxus cuspidata].

In order to study the active constituents in the stem barks of Taxus cuspidata Sieb. et Zucc., led to the isolation and structural determination of three compounds. On the basis of chemical evidences and spectral analysis (UV, IR, 1HNMR, 13CNMR and FAB-MS,) the structures of I, II and III were elucidated as baccatin I 1-hydroxy, taxinine J 2-deacetoxy and beta-sitosterol. Compound I was found from this plant for the first time.

Alkaloids↗

PubMed1998

Cardiac hypertrophy in copper-deficient rats is owing to increased mitochondria.

Dietary copper depletion results in cardiac hypertrophy and ultrastructural alterations. The objective of this study was to determine the components that contribute to cardiac enlargement. Two groups (n = 4) of male, weaning, Sprague-Dawley rats were fed ad libitum with copper-adequate or copper-deficient diets for five weeks. Cross sectional transmission electron micrographs from both groups were evaluated using image analysis to quantify absolute area occupied by myocyte, mitochondria, myofibril, and other intracellular material. Copper-deficient rats had larger myocytes, increased area of mitochondria, and increased ratio of mitochondria:myofibril as well as mitochondria:myocyte. Copper deficiency did not change the absolute area occupied by myofibrils. These data suggested that increase in the absolute mitochondria area is the major contributory factor to the cardiac hypertrophy in copper deficiency. Under the conditions used, myofibril has minimal role toward contributing to the hypertrophic state. The pathology reported resembles human forms of genetic mitochondrial cardiomyopathies. The copper-deficient rat may be a useful model to investigate the underlying biochemical or molecular responses when peptides of enzymes are deleted.

Animals↗

PubMed1998

[Verification of a new processing technology for pilot production of Aconitum coreanum (Lévl.) Raipaics].

The stability and feasibility of a new technology for processing Aconitum coreanum have been tested for pilot production by determining the components, toxicity(LD50) and traditional identification standard. The result shows that the contents of guanfu A and total alkaloid between the small trial and pilot production are slightly different and LD50 are nearly similar. Hypaconitine was not found in all kinds of processed products. The new technology has thus been proved stable and feasible.

Alkaloids↗

PubMed1998

[Application and characteristics of macroreticular resin in purification study of different effective ingredients in Chinese medicines].

OBJECTIVE: To evaluate the possibility of applying macroreticular resin to the purification of different effective ingredients in Chinese medicines and study its working characteristics. METHOD: Four samples (water extracts of four single Chinese medicinal materials) containing alkaloids, anthraquinones, water soluble phenols and inorganic salts were employed. RESULT: LD605 resin is able to adsorb different effective ingredients except inorganic salts. CONCLUSION: Purification of Chinese compound prescriptions can be achieved by means of macroreticular resin.

Adsorption↗

PubMed1998

[Protective effects of Ginkgo biloba extract on focal cerebral ischemia and thrombogenesis of carotid artery in rats].

Rat focal cerebral ischemia induced by occlusion and thrombogenesis of middle cerebral artery(MCAO) was used as experimental model to study the effects of extract of Ginkgo biloba (EGb) and the positive control drugs were urokinase and nimodipine on cerebral infarct size and neurological deficits. The results showed that cerebral ischemia and neurological deficits appeared in rat focal cerebral ischemic models, and the degree was of cerebral ischemia larger in occlusion model than in thrombogenesis model. The cerebral infarct size was significantly smaller and neurological deficits greatly improved at large dose of EGb(200 mg.kg-1, i.v.), the preventive effect appeared to be better than the treatment effect. The positive control drugs urokinase and nimodipine were also shown to distinctly decrease the cerebral infarct size and improve the neurological deficits in the models. Small dose of EGb(100 mg.kg-1, i.v.) was found to decrease the cerebral infarct size of thrombogenesis model, and improve neurological deficits of both thrombogenesis and occlusion model. EGb was also shown to inhibit the thrombogensis of rat common carotid artery stimulated by electrical current in dose-dependent manner. This experiment indicates that EGb might have beneficial effects on prevention and treatment of ischemic stroke and thrombogenesis.

Animals↗

PubMed1998

[A method for standardizing brain CT image].

In this paper, we propose the concept of standardization of brain CT image and introduce a kind of standardization method based on geometry correction technique. To work out the method, first we preprocessed the raw CT image, second automatically searched the control points which were used for establishing the correction equation, and last we completed the standardization of the CT image. The result of the experiments demonstrated the pracficability efficiency of this kind of method which conld provide theoretical foundation and experimental means for the diagnosis of brain disease.

Algorithms↗