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Biomedical subjects

X J Liu

Publications and source records attributed to X J Liu.

At least 109 records · Page 6Linked to original sources
PubMed1990

Gene expression during tuber development in potato plants.

Potato tubers are modified stems that have differentiated into storage organs. Factors such as day-length, nitrogen supply, and levels of the phytohormones cytokinin and gibberellic acid, are known to control tuberization. Morphological changes during tuber initiation are accompanied by the accumulation of a characteristic set of proteins, thought to be involved in N-storage (i.e. patatin) or defense against microbial or insect attack (i.e. proteinase inhibitor II). Additionally, deposition of large amounts of starch occurs during tuber formation, which is paralleled by an increase in sucrose synthase and other enzymes involved in starch biosynthesis (i.e. ADP-glucose pyrophosphorylase, starch synthases, and branching enzyme). Potential controlling mechanisms for genes expressed during tuberization are discussed.

Carboxylic Ester Hydrolases↗
PubMed1990

cis regulatory elements directing tuber-specific and sucrose-inducible expression of a chimeric class I patatin promoter/GUS-gene fusion.

The 5'-upstream region of the class I patatin gene B33 directs strong expression of the beta-glucuronidase (GUS) reporter gene in potato tubers and in leaves treated with sucrose. Cis-acting elements affecting specificity and level of expression were identified by deletion analysis in transgenic potato plants. A putative tuber-specific element is located downstream from position -195. Nuclear proteins present in leaf and tuber extracts bind specifically to a conserved AT rich motif within this region. A DNA fragment between -183 and -143, including the binding site is, however, not able to enhance the expression of a truncated 35S promoter from cauliflower mosaic virus. Independent positive elements contributing to a 100-fold increase relative to the basic tuber-specific element are located between -228 and -195; -736 and -509, -930 and -736 and -1512 and -951. Sucrose inducibility is controlled by sequences downstream of position -228, indicating that the tuber-specific and sucrose-inducible elements are in close proximity.

Binding Sites↗
PubMed1990

Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies.

A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.

Adult↗
PubMed1990

111In-antimyosin antibody imaging for detection of myocardial infarction: a quantitative approach.

Indium-111-antimyosin imaging has been shown to be a sensitive and specific method for detecting myocardial necrosis, but a quantitative method for interpretation of 111In-antimyosin planar images is lacking. A prospective study was performed in 114 patients with suspected acute myocardial infarction using planar 111In-antimyosin imaging. A ratio of maximum myocardial uptake counts (H) (9 X 9 pixels) over adjacent lung background (L), i.e. H/L ratio, was obtained from 24 and 48 h images. This value was compared with peak creatine kinase (CK) enzyme and left ventricular ejection fraction (LVEF). The patients were classified into groups based upon standard criteria for Q-wave acute myocardial infarction (Q-MI) (n = 50), non-Q-MI (n = 21), unstable angina (n = 15) and those with no evidence of MI or ischaemia (n = 28). The mean +/- S.D. H/L ratio in the Q-MI group was 2.28 +/- 0.50 (24 h, left anterior oblique, LAO, view) and was greater than the non-Q-MI group (1.98 +2- 0.30) (P less than 0.02). In patients with unstable angina (UA), seven had a high ratio (1.75 +/- 0.29) and eight had a lower ratio (1.29 +/- 0.07). In the group of patients without MI or UA, the ratio was 1.24 +/- 0.11 and this was significantly lower than the Q-MI and non-Q-MI groups and those patients with UA and positive 111In uptake (P less than 0.001, respectively). However, there was no significant difference between old MI and patients without evidence of MI or UA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Pathological changes of the optic nerve from compression by the internal carotid artery].

The optic nerve in relation to the internal carotid artery was anatomically and pathologically studied in 51 adult brain specimens. There were obvious impressions on the optic nerves from compression by the sclerosed internal carotid arteries, and pathological changes in the optic nerves, such as atrophy, were observed in 6.9% of the specimens. This fact suggests that clinical visual defects of unknown explanation may be caused by the indurative internal carotid artery compressing the optic nerve.

Adolescent↗
PubMed1989

Clinical evaluation of the 99mTc-CPI myocardial perfusion imaging.

99mTc-CPI myocardial perfusion scintigraphy including planar images in 35 patients and SPECT images in 16 patients has been studied. Scintigraphic data revealed that high quality 99mTc-CPI myocardial perfusion images were obtained. The sensitivity and specificity of 99mTc-CPI planar images in detecting CAD was 92% and 80% respectively. There was no significant difference in sensitivity for detecting CAD between planar and SPECT. However, the specificity of SPECT was much better than that of planar imaging.

Adult↗
PubMed1989

Preoperative diagnosis and management of pheochromocytoma.

To improve the diagnosis and management of pheochromocytoma, the results from a comparative study of 34 patients with pheochromocytoma, 33 patients with essential hypertension and 36 normal volunteers are presented. Our data suggest that clinical characteristics indicate the possibility of pheochromocytoma only, while the definite diagnosis of pheochromocytoma must be based on comprehensive analysis of all data obtained from both clinical and laboratory studies. The plasma concentration of free norepinephrine in peripheral veins is helpful in establishing the presence or absence of pheochromocytoma. Both CT scan and meta-I-131-iodobenzylguanidine images are useful noninvasive techniques for localization of pheochromocytoma. Phenoxybenzamine is of benefit in both diagnosis and management of patients with pheochromocytoma.

Adolescent↗
PubMed1988

Measurements of the effects of percutaneous nitroglycerin on left ventricular performance in patients with coronary artery disease with a cardiac probe.

Left ventricular function was measured after percutaneous nitroglycerin in ten patients with coronary artery disease under double blind random control. The elevation of LVEF after percutaneous nitroglycerin paste (containing 10 mg nitroglycerin) was 8.3% +/- 1.3% (P less than 0.001) at 30 min, 8.5% +/- 1.8% (P less than 0.001) at 60 min, 10.1% +/- 1.8% (P less than 0.001) at 90 min and 8.7% +/- 2.2% (P less than 0.01) at 120 min respectively, but the change of LVEF after nitroglycerin ointment (containing 5 mg nitroglycerin) was not significant. The elevation of ER and RCO after nitroglycerin paste were 0.448 +/- 0.088 (EDV/s) (P less than 0.001), 6.73 +/- 1.47 (EDV/s) (P less than 0.01) at 30 min, 0.376 +/- 0.078 (P less than 0.001), 6.64 +/- 1.36 (P less than 0.001) at 60 min, 0.456 +/- 0.089 (P less than 0.001), 8.02 +/- 2.11 (P less than 0.001) at 90 min and 0.358 +/- 0.076 (P less than 0.01), 6.18 +/- 2.05 (P less than 0.01) respectively. It was demonstrated that percutaneous nitroglycerin paste (10 mg nitroglycerin) can improve the left ventricular function of patients with coronary artery disease.

Administration, Topical↗
PubMed1987

Monitoring effects of alpha-human atrial natriuretic polypeptide (alpha-hANP) on left ventricular function in patients with essential hypertension with a cardiac probe.

The effects of alpha-hANP on left ventricular function were studied with a cardiac probe in ten patients with essential hypertension. Our data showed that intravenous administration of alpha-hANP significantly elevated left ventricular function. At 5 min, the elevation of EF, RCO, ER, RSV, PFR were 13.23% (P less than 0.02), 12.7 (P less than 0.02), 0.618 (P less than 0.02), 0.133 (P less than 0.05), 0.283 (P less than 0.01), respectively. At 10 min, the increase of EF, ER, were 11.07% (P less than 0.02) and 0.233 (P less than 0.01), respectively. Atriopeptin significantly reduced systolic and diastolic blood pressure from 2 min to 20 min (P less than 0.001-0.05).

Adult↗
PubMed1987

Clinical evaluation of the 99mTc-labeled myocardial imaging agent, hexakis (t-butylisonitrile)-technetium.

99mTc-TBI myocardial perfusion imaging has been studied in 7 normal subjects and 24 patients with coronary artery disease. Scintigraphic data revealed that 99mTc-TBI myocardial perfusion imaging is more sensitive than ECG in detecting myocardial infarction. In comparing 99mTc-TBI imaging with contrast angiography, its' sensitivity for the diagnosis of coronary artery disease was 91.7%.

Adult↗