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Biomedical subjects

L Liang

Publications and source records attributed to L Liang.

157 records · Page 9Linked to original sources
PubMed1984

The optimal conditions for microtiter cultures of human peripheral lymphocytes. II. Effects of mitogen concentration, incubation time and duration of isotope pulse.

The optimal conditions for obtaining the highest cell proliferation was studied in microtiter culture of human lymphocytes. The peak lymphocyte proliferation was obtained in 4-day cultures with PHA 1 microgram/ml or Con A 9 micrograms/ml. The cells incorporate increasing amounts of 3H-thymidine proportional to the period of isotope incubation, at least up to 18 hours.

Cells, Cultured↗
PubMed1977

Repression of the tyrosine, lysine, and methionine biosynthetic pathways in a hisT mutant of Salmonella typhimurium.

A comparison was made of the repressibility of certain enzymes in the tyrosine, methionine, and lysine biosynthetic pathways in wild-type Salmonella typhimurium and a hisT mutant. The results show that (i) tyrosine represses the synthesis of the tyrosine-sensitive 3-deoxy-D-arabino-heptulsonic acid 7-phosphate synthetase and the tyrosine aminotransferase to the same extent in a hisT mutant as in wild type and (ii) there is no detectable alteration in the extent to which methionine represses O-succinylhomoserine synthetase or in the extent to which lysine represses the lysine-sensitive beta-aspartokinase as a result of the hisT mutation.

2-Isopropylmalate Synthase↗
PubMedDate not supplied

III. New developments: 2. Virtual MR endoscopy in the central nervous system.

Recent advances in three-dimensional (3D) data acquisition and postprocessing technologies have been playing a important role in widening the potential applications of 3D display. The authors described new applications of a virtual endoscopic algorithm for 3D display of high resolution MR images: (a) intracranial intravascular virtual MR endoscopy using the 3D fast imaging with steady state precession (FISP) sequence, and (b) virtual MR endoscopy of the cerebrospinal fluid (CSF) spaces using the constructive interference in steady state (CISS) three-dimensional Fourier transform (3DFT) sequence. The virtual endoscopic images were displayed with use of a commercially available perspective volume-rendering algorithm. Our initial experience showed that virtual MR endoscopy can be performed to observe the intracranial arteries and CSF spaces from the viewpoints within themselves. Although the clinical use of the intracranial virtual MR endoscopy has not been established yet, the images obtained are very attractive and further investigations in this field will be expected.

Central Nervous System↗
PubMedDate not supplied

Effect of portal venous flow augmentation on liver enhancement with CT.

BACKGROUND: The purpose of this study was to evaluate the effect of portal flow augmentation on hepatic computed tomographic (CT) enhancement. METHODS: Thirteen patients undergoing follow-up CT of the liver within 6 months of initial study ingested 470 mL of Ensure 30 min before the second examination. Contrast medium injection and scanning parameters were identical for both studies. RESULTS: The time to peak and the maximum and mean liver enhancements were 68 s, 56 HU, and 46 HU, respectively, for the examinations without Ensure and 68 s, 53 HU, and 44 HU for the examinations with Ensure. No significant difference was found between the two groups when mean liver enhancement was calculated over 3-s time intervals. CONCLUSION: Portal venous flow augmentation induced by a meal had no effect on liver enhancement.

Contrast Media↗
PubMedDate not supplied

Skull base tumors: evaluation with contrast-enhanced MP-RAGE sequence.

The purpose of this study is to assess the value of contrast-enhanced MP-RAGE sequence for evaluation of skull base tumors. A total of 36 patients were prospectively evaluated. MP-RAGE showed relatively higher CNRs than other sequences, and there was a significant difference of CNR between the MP-RAGE and contrast T1-weighted SE images when fat tissue was chosen as the background. MP-RAGE was significantly superior to other sequences in the diagnosis of the extent of tumors. Contrast-enhanced MP-RAGE sequence is useful in evaluation of skull base tumors because of its higher contrast, higher spatial resolution, multiplanar capability, and suppression of the fat signal.

Adolescent↗
PubMedDate not supplied

Plasma levels of matrix metalloproteinase-9 in Henoch-Schönlein purpura.

OBJECTIVE: To investigate the potential role of matrix metalloproteinase-9 (MMP-9) in Henoch-Schönlein purpura (HSP), an acute type of systemic vasculitis in children. METHODS: In this study, 24 children with HSP and ten healthy children (HC) were enrolled from February 2003 to July 2004. Blood samples were obtained from all the children. The total levels of MMP-9 in the plasma were detected by enzyme-linked immunosorbent assay (ELISA). The second blood samples were obtained from eight of the 24 HSP patients in the convalescent phase. MMP-9 of circulating white blood cells was detected by immunocytochemistry. RESULTS: Plasma MMP-9 levels in the acute phase of HSP (249.75 ng/mL) were significantly higher than in HC (191.00 ng/mL) (p = 0.034). Immunocytochemistry showed that MMP-9 was positive in the circulating white blood cells. The MMP-9 levels in the convalescent phases were lower than in the acute phase in six cases, but increased in the other two cases, and one of these two cases had recurrence of purpuric rashes in the lower extremities for 3 months. CONCLUSION: MMP-9 plays an important role in the vascular destruction of HSP, and circulating white blood cells may be a source of the MMP-9 secreted into the circulation.

Acute Disease↗
PubMedDate not supplied

Determination of methyl mercury in whole blood by ethylation-GC-CVAFS after alkaline digestion-solvent extraction.

A method for the determination of methyl mercury in whole blood samples based on ethylation-gas chromatography-cold vapor atomic fluorescence spectrometry after alkaline digestion-solvent extraction is described. The extraction procedure and conditions were optimized, and the matrix interference after extraction was critically investigated. The storage stability of MeHg in blood samples and a series of extracts was determined. The method detection limit was found to be approximately 0.02 ng/g for a 0.5-g blood sample with relative standard deviations of less than 10%. The accuracy and precision were evaluated by summarizing the quality-control (QC) data generated over a one and one half year period. Appropriate procedures for sample collection, transportation, and storage were adapted to the method. Using this method accompanied by explicit QC protocols and procedures, background levels of MeHg and total mercury in blood for 150 8-10-year-old Portuguese children with nonoccupational and nonamalgamal exposure were determined and reported with summarized QC data.

Child↗
PubMedDate not supplied

Contrast-enhanced CISS MRI of vestibular schwannomas: phantom and clinical studies.

PURPOSE: The purpose of this work was to assess the changes of signal intensity on constructive interference in steady state (CISS) 3D Fourier transformation (3DFT) MRI after administration of Gd-DTPA and to evaluate the efficacy of contrast-enhanced CISS-3DFT MRI to depict the seventh and eighth cranial nerves affected by vestibular schwannomas. METHOD: All scans were carried out on a 1.5 T MR unit. First, an experimental study was conducted to evaluate the changes in signal intensity of the CISS-3DFT sequence in relation to the concentration of contrast medium. Second, nine consecutive patients with 11 vestibular schwannomas underwent CISS-3DFT imaging before and after contrast agent administration. Signal intensities of the tumors and nerves were measured and compared between the pre- and postcontrast images. Visualization of the facial and cochlear nerves was rated on pre- and postcontrast CISS imaging independently. RESULTS: On the phantom study, the CISS-3DFT sequence showed a constant increase in signal intensity as the concentration of Gd-DTPA increased. The contrast between the nerves and tumors significantly increased after contrast agent administration (from 0.1 to 9.0 as mean contrast-to-noise ratio). The ability to depict the nerves was also significantly higher for postcontrast CISS-3DFT imaging than for precontrast. CONCLUSION: Although the CISS-3DFT sequence offers similar contrast as other heavily T2-weighted sequences, the signal intensity of contrast-enhanced tumors increased on CISS-3DFT imaging. Contrast-enhanced CISS imaging was valuable for evaluating the seventh and eighth cranial nerves affected by vestibular schwannomas.

Adult↗
PubMedDate not supplied

Perfusion-sensitive MRI of cerebral lymphomas: a preliminary report.

PURPOSE: To date, there have been no systematic reports examining cerebral lymphomas with perfusion-sensitive MRI. We sought to determine the characteristics of perfusion-sensitive MRI of these tumors. METHOD: Five primary and three secondary cerebral lymphomas were analyzed. None of the patients had a history of AIDS. Various areas of relative cerebral blood volume (rCBV) within tumor were analyzed, and maximum CBV ratios (CBV[tumor/contralateral]) were identified for evaluation. RESULTS: In three primary and three secondary cerebral lymphomas, maximum CBV ratios were <2.5 (mean 1.50). In others, maximum CBV ratios were markedly higher than those of the white matter (5.38 and 5.42). Mean maximum rCBV ratios of primary and secondary cerebral lymphomas were 2.93 and 1.43, respectively. There was no significant difference between the two groups. CONCLUSION: Cerebral lymphomas had a tendency to have low rCBV values. This information may be helpful in diagnosing these tumors.

Adult↗