Biomedical subjects

R S Liu

Publications and source records attributed to R S Liu.

At least 91 records · Page 5Linked to original sources

PubMed1995

The "Fisherman's Waders" sign in a bone scan of inferior vena cava thrombosis associated with nephrotic syndrome.

This paper presents a 61-year-old male patient with nephrotic syndrome, hypercoagulability and IVC thrombosis. Increased soft tissue uptake below the level of the mid chest was seen in his bone scan. The term "Fisherman's Waders" sign is suggested for this finding, whose recognition may permit the identification of inferior vena cava obstruction in bone scans. The existence of a cavo-portal shunt was also confirmed by dynamic scintigraphy.

Blood Coagulation Disorders↗

PubMed1995

Long-term culture of primary B cells and in vitro expression of an exogenous gene.

Efficient introduction and expression of exogenous genes into primary B cells is very important to study B-cell biology and is essential for gene therapy. These efforts have often been impeded by the lack of availability of a simple culture condition for growth and proliferation of primary B cells as well as the lack of vehicles for efficient introduction of genes of interest. In this communication, we have developed a culture condition that supports the growth of primary B cells from beta-gal-immunized mouse spleen for 30 days without the aid of feeder layers. During this period, B cells secreted polyclonal antibodies into the medium. To study expression of an exogenous reporter gene, human growth hormone (hGH) was introduced into cultured B cells using retroviral vectors. hGH was expressed up to 21 days in the absence of drug selection and the infected cells continued to secrete immunoglobulins into the medium.

Animals↗

PubMed1995

Lipiodol uptake and retention by human hepatoma cells.

Lipodol has important diagnostic and therapeutic uses in hepatoma. However, the mechanisms of its selective, prolonged retention in hepatoma cells is not well understood. Therefore, using oil-red O, light and electron microscopy and neutron activation analysis we have determined that HepG2 cells are characterized by lipiodol deposition and emulsification on the cell surface, action uptake of lipodol by endocytosis, and prolonged intracellular retention. These findings may have major clinical significance in the development of a new treatment for hepatoma patients.

Carcinoma, Hepatocellular↗

PubMed1995

Evaluation of the biodistribution and in vivo biochemistry of 99mTc-cysteine and 99/99mTc-cysteine complexes--a potential renal imaging agent.

Cysteine was chelated with 99mTc and/or 99Tc in a freeze-dried kit containing Tin(II) ions, and the yellow 99m/99Tc-cysteine complex (complex I) was separated to study the biodistribution. Comparison of the distribution of 99m/99Tc-cysteine and 99mTc-cysteine complexes was made in rats and mice. The renal excretion patterns were studied in rats in the presence and absence of the renal tubular transport inhibitor 2,4-dinitrophenol. The carrier of Tc-cysteine complex in the blood and also the radioactive compounds in the urine were studied by HPGFC and SDS-electrophoresis. The kidney was confirmed as the target organ; serum albumin serves as a carrier for transport of Tc-cysteine complex to the kidney. The Tc-cysteine complex was the primary form in excreta, and glomerular filtration was the dominant excretory pathway.

Animals↗

PubMed1995

Tc-99m phytate bone marrow scintigraphy showing multiple areas of focal hyperactivity in a patient with lung cancer. A case report.

Focal hyperactivity indicative of metastases is a rare finding in bone marrow imaging. In a lung cancer patient with multiple bony metastases, the Tc-99m phytate bone marrow imaging revealed multiple focal areas of increased radioactivity corresponding to the bone scan findings. The findings presented are consistent with a previous animal study, which found that phytate distribution was similar to that of diphosphonate in the skeletal system of rats and rabbits. The authors conclude that Tc-99m phytate should not be used as a bone marrow imaging agent. Further studies of Tc-99m phytate bone marrow scintigraphy on human beings are under way.

Aged↗

PubMed1995

Three-phase abdominal scintigraphy in lupus vasculitis of the gastrointestinal tract.

Gastrointestinal vasculitis is a recognized but frequently misdiagnosed complication of systemic lupus erythematosus. The authors investigated the usefulness of three-phase Tc-99m pyrophosphate abdominal scintigraphy for identifying areas of vasculitis in patients with systemic lupus erythematosus who have gastrointestinal symptoms (diarrhea or abdominal pain). Among patients with gastrointestinal symptoms, 62 of 82 (75%) patients showed positive scan results, suggesting gastrointestinal vasculitis. Among patients without gastrointestinal symptoms, 6 of 43 (13%) patients showed positive scan results. Although three-phase Tc-99m pyrophosphate abdominal scintigraphy cannot provide a definite diagnosis of vasculitis of the gastrointestinal tract, it is a noninvasive and convenient method for suggesting and monitoring gastrointestinal vasculitis.

Abdomen↗

PubMed1995

Hypertrophic pulmonary osteoarthropathy in nasopharyngeal carcinoma: an early sign of pulmonary metastasis.

The aims of this study were to determine the incidence of hypertrophic pulmonary osteoarthropathy (HPO) in nasopharyngeal carcinoma (NPC) and assess its clinical significance. Altogether, 407 NPC patients were reviewed retrospectively. HPO was identified by 99Tcm-methylene diphosphonate bone scans and related clinical and radiographic evidence. Pulmonary metastases, bony metastases and titre of anti-Epstein Barr virus (EBV) immunoglobulin were assessed in patients with and without HPO. The patients had a mean (+/- S.D.) age of 50.4 +/- 12.4 (range 17-73) years. HPO was found in 27 of the 407 (6.6%) NPC patients, among whom 13 (48%) had pulmonary metastases. HPO preceded lung metastases by 7-22 months (14.4 +/- 6 months) in 7 (52%) patients. Six patients had overt lung metastases at the time of the bone scan. No significant difference was found in anti-EBV immunoglobulins between the patients with or without HPO, nor in the incidence of bony metastases between these two groups of patients. HPO should be regarded as an early sign of pulmonary metastases.

Adolescent↗

PubMed1995

Photostationary state compositions of retinal and related compounds included in beta-lactoglobulin. Effects of protein host on isomer distribution of polyene substrates.

The UV-visible absorption spectra and photostationary state compositions of retinal (or the related C-18 ketone, 3-dehydroretinal and the C-22 aldehyde) imbedded in the binding cavity of beta-lactoglobulin (BLG) are consistent with the view that the carbonyl group of these polyenes are hydrogen-bonded with the protein host, most likely with the lone protonated lysine residue in the binding pocket. Patterns of variation in photochemical behavior of the imbedded chromophore versus that in solution are discussed in terms of possible specific protein-substrate interactions. The results are also compared with that of the methyl ether of retinol where similar hydrogen bonding is not possible.

Chemical Phenomena↗

PubMed1995

Early effects of Gamma Knife surgery on malignant and benign intracranial tumors.

To assess the early response of intracranial tumors to Gamma Knife surgery, we performed a prospective investigation of 42 patients treated by Gamma Knife surgery for different types of intracranial tumors. The clinical condition, tumor volume, treatment results and their temporal correlation with the irradiation were analyzed, based on MRI performed on the same MR scanner. Volume reduction in the tumors measured at the latest follow-up ranged from 0.2 to 100%. All except 1 malignant tumor showed decreasing size and improving peritumoral edema 1-7 months after radiosurgery. In 30 benign tumors, 13 showed either a decrease or no change in volume. However, an initial volume increase was observed in 17 tumors, with a maximum at 3-9 months, which subsequently regressed. In 2 meningioma patients, peritumoral edema increased and needed steroid treatment. Sequential PET-FDG imaging of the patients showed decreasing FDG uptake, indicating a decrease tumor in metabolism. The PET findings correlated well with the loss of contrast enhancement on MR images. In conclusion, intracranial tumors respond to Gamma Knife surgery from an early stage. Different tumors have different responses to radiosurgery. It is too early to offer a prognosis of long-term effects based on the limited material. However, sequential clinical, MR and PET follow-ups provide an excellent opportunity to investigate the evolving irradiation effects in vivo.

Brain Neoplasms↗

PubMed1995

Early irradiation effects observed on magnetic resonance imaging and angiography, and positron emission tomography for arteriovenous malformations treated by Gamma Knife radiosurgery.

In 14 patients (7 males and 7 females, age 16-49, mean 29 years), medium-to-large arteriovenous malformations (AVMs; nidus volume 3.5-17.5 cm3, mean 9.4 cm3) were treated by Gamma Knife radiosurgery. Stereotactic MR and conventional angiography were included for targeting to improve targeting accuracy and tissue content in the irradiation volume. Maximum irradiation doses to the nidi were 36-40 Gy (mean 38.9 Gy) and minimum target doses were 18-24 Gy (mean 20 Gy). MR images and MR angiography demonstrated decreasing caliber of feeding vessels and AVM nidus volumes from an early stage, 3 months after radiosurgery, which indicated improvement in cerebral hemodynamics. The improvement correlated well with that observed on PET using [18F]fluorodeoxyglucose (FDG) and with the patients' clinical condition. MR creates an opportunity to monitor treatment effects in a completely noninvasive manner, while conventional angiography remains necessary for verifying complete obliteration of AVMs. More patients and longer follow-ups are needed for clarifying the role of MR techniques in radiosurgery for AVMs.

Adolescent↗

PubMed1995

99Tcm-HMPAO and 99Tcm-DTPA radioaerosol clearance measurements in idiopathic pulmonary fibrosis.

The clearance rate of an inhaled aerosol of a lipophilic complex, 99Tcm-hexamethylpropyleneamine oxime (99Tcm-HMPAO), was compared with that of a hydrophilic complex, 99Tcm-diethylenetriamine pentaacetate (99Tcm-DTPA), in nine normal subjects and in eight patients with idiopathic pulmonary fibrosis (IPF). Data were acquired as follows. The subjects were placed supine with their back against the scintillation camera and breathed aerosol for 2 min; pulmonary radioactivity was then monitored for 30 min. A time-activity curve (TAC) was generated from the region of interest (ROI) over the periphery of each lung field and a computer program was then used to calculate percentage clearance per minute (k) in each lung. The mean (+/- S.E.M.) rate of clearance of 99Tcm-DTPA (k = 1.31 +/- 0.13% min-1) was not significantly different from that of 99Tcm-HMPAO (k = 1.32 +/- 0.27% min-1, P > 0.025) in the normal subjects. However, 99Tcm-DTPA clearance was 1.91 +/- 0.27% min-1 and 99Tcm-HMPAO clearance 0.78 +/- 0.17% min-1 in eight patients with IPF (P < 0.001, 99Tcm-DTPA vs 99Tcm-HMPAO). By regression analysis using a multiplicative model, both values correlated fairly [r = -0.71, y = exp (0.08-0.85 ln chi); P < 0.005], with a change in clearance rate in the opposite direction in all eight patients. The results of our study demonstrate that the pulmonary clearance of 99Tcm-HMPAO is different from that of 99Tcm-DTPA in IPF.

Aerosols↗

PubMed1995

An appraisal of dipyridamole thallium imaging-detected ischemia in Chinese following acute myocardial infarction.

BACKGROUND: The detection of objective myocardial ischemia is an important work-up of risk stratification for survivors of acute myocardial infarction (MI). Intravenous dipyridamole thallium scintigraphy was used to identify the prevalence and prognostic value of silent myocardial ischemia (SI) at the early stage in patients after MI. METHODS: Ninety patients (male/female = 87/3; aged from 36 to 70 years) who succumbed to an episode of MI was recruited in this prospective study. Thallium imaging with reversible or combined defect was defined as presence of SI (Group I), while those with fixed defects or normal images were defined as absence of SI (Group II). Correlation between the patterns of thallium images for postinfarct ischemia and the angiographic lesions was investigated. Also, versatile clinical variables and indexes of adverse cardiac events: unstable angina, CHF, reinfarction, ventricular tachyarrhythmia and sudden death, were evaluated for their influence on patients' prognosis. The average follow-up was 11.6 months. RESULTS: There were 61 patients in the Group I as compared with 29 patients in the Group II. The difference of Killip functional classification between Group I and Group II patients was not significant (1.33 +/- 0.72 versus 1.07 +/- 0.59). Adverse cardiac event occurred in 30% (27/90) of the patients during follow-up. Cardiac death occurred in 6 cases (7%) and were distributed evenly (3 versus 3) in both groups. Group I patients showed a higher number of nonfatal reinfarctions (8 versus 5) and had more cases of percutaneous coronary angioplasty (11 versus 8) than Group II patients. Only two cases in Group I underwent bypass graft surgery. There was no statistic difference among four patterns of thallium image in the cumulative event-free survival curve. Prior history of CHF, prior MI and higher score index of proximal arterial stenosis were the three significant prognostic predictors for late cardiac events. CONCLUSIONS: Dipyridamole thallium imaging-detected SI was frequently seen in the Chinese patients following AMI. It was less valuable than prior histories of CHF, prior MI and higher index of proximal arterial stenosis scores in predicting the short-term unfavorable cardiac events in these patients. A large scale analysis and longer follow-up might be required to more accurately determine the role of this exam for the Chinese victims of myocardial infarction.

Adult↗

PubMed1995

Tc-99m MDP uptake in cerebral infarction: comparison with Tc-99m DTPA brain scan and Tc-99m HMPAO brain SPECT.

Intracerebral uptake of methylene diphosphonate (MDP) was unexpectedly found in metastatic work-up of lung cancer. The history of the 52-year-old patient revealed a sudden onset of weakness of right limbs 10 days ago. Technetium-99m diethylenetriamine pentaacetate (Tc-99m DTPA) brain scan and Tc-99m hexamethyl propylene amine oxime (HMPAO) brain single photon emission computed tomography (SPECT) were done, and both showed abnormality in the left temporoparietooccipital region corresponding to the territory of left middle cerebral artery. A repeated bone scan four months later showed complete resolution of the intracerebral Tc-99m MDP uptake. We present this case to emphasize the importance of complementary and enhanced radionuclide images.

Brain↗

PubMed1995

Biliary motility following endoscopic sphincterotomy for recurrent common bile duct stones.

BACKGROUND: Recurrent common bile duct (CBD) stones after cholecystectomy are a common biliary tract disease. The role of biliary emptying in the formation of these stones is not yet well defined. METHODS: Cholescintigraphy was used to evaluate the biliary motility in 50 cholecystectomized patients with recurrent CBD stones after endoscopic sphincterotomy (EST) with stone extraction. Complete clearance of the CBD stones was confirmed in all patients by endoscopic retrograde cholangiopancreatography. Absence of sphincter of Oddi (SO) pressure after EST was determined by means of biliary manometry, and 99mTc-diisopropyl iminodiacetic acid (DISIDA) cholescintigraphy was performed four to six weeks after recovery from sphincterotomy. RESULTS: Complete clearance of the radioisotopes from the bile duct within 1, and more than 1 hour, was observed in 3 (6%) and 47 (94%) of the patients, respectively. When a cutoff value of 2 hours indicating abnormal biliary motility was employed, 31 out of the 50 patients (62%) had delayed biliary emptying. In comparing the clinical parameters between the two groups, patients with delayed biliary emptying time demonstrated an increase in CBD size greater than those of the normals (11.7 +/- 0.5 vs 9.2 +/- 0.4 mm, p < 0.05), while the presence of juxtapapillary diverticula and length of time for recurrence of CBD stones after cholecystectomy were not significant. Follow-up study showed that repeated recurrence rate of CBD stones appeared to be higher in the patients associated with delayed (12.9%) rather than normal (5.3%) biliary emptying. CONCLUSIONS: These results suggested that, in the absence of a functioning SO, abnormal biliary motility in cholecystectomized patients is one of the clinical factors involved in the pathogenesis of recurrent CBD stones.

Adult↗

PubMed1994

Enhanced immunogenicity of leucine enkephalin following coupling to anti-immunoglobulin and anti-CD3 antibodies.

Leucine enkephalin (Leu-enk) was coupled to both T and B cell antibodies in order to investigate the possibility of enhanced immunogenicity via targeted immunization. The two antibodies used were Hm x Mo CD3 and Gt x Mo Ig, respectively. The data indicate that while both antibody carriers enhanced the immunogenicity of Leu-enk, the use of the Hm x Mo CD3 antibody resulted in a greater number of mice with positive Leu-enk specific serum titers. 12 Leu-enk cell lines were produced and one, LE4H8, was chosen for characterization.

Amino Acid Sequence↗

PubMed1994

Reappraisal of scrotal scintigraphy in evaluation of varicocoeles.

Varicocoeles could be classified into stop-type and shunt-type. In stop-type varicocoeles, only the internal spermatic (testicular) vein is dilated and needs to be ligated. In shunt-type, both internal spermatic vein and external spermatic (cremasteric) vein are dilated due to incompetence of the cremasteric system and both venous systems require ligation. Two-phase (flow and static) scrotal scintigraphy was performed on 92 patients preoperatively. Forty-three patients in whom the testicular and cremasteric veins could be verified during operation were included in this study. All 43 patients had unilateral varicocoeles and had abnormal blood pooling in the affected spermatic cord and hemiscrotum. In the blood flow study, 22 of 27 shunt-type varicocoeles had abnormal flow in the spermatic cord whereas only one out of 16 stop-type varicocoeles had increased blood flow. No difference in the results of semen analysis was found between the two groups of patients. Two-phase scrotal scintigraphy provides a noninvasive evaluation of shunting of the retrograde venous flow from the internal spermatic to the external spermatic vein. Understanding this pathophysiological change would be of benefit in the decision making about a surgical approach to varicocoeles.

Humans↗

PubMed1994

Efficacy of quantitative cholescintigraphy in the diagnosis of sphincter of Oddi dysfunction.

The diagnostic efficacy of time-activity curves (TAC) and common bile duct dynamics (CBDD) derived from quantitative cholescintigraphy (QC) was assessed in patients with suspected sphincter of Oddi dysfunction (SOD). Quantitative cholescintigraphy was performed on 34 cholecystectomized individuals with suspected SOD and 26 asymptomatic controls. Each patient with suspected SOD underwent endoscopic retrograde cholangiography and sphincter of Oddi manometry (SOM). After exclusion of eight patients because of failure of manometry, the final diagnoses of the remaining 26 patients were taken as the gold standard by which to determine the detectability of TAC and CBDD. The sensitivity of TAC reached 68.8%. Common bile duct dynamics showed equal sensitivity but was more specific than TAC. The sensitivity improved to 87.5% when TAC and CBDD were combined. We conclude that non-invasive QC provides good sensitivity and specificity in evaluating cholecystectomized patients with suspected SOD.

Aged↗

PubMed1994

Shape of the chromophore binding site in pharaonis phoborhodopsin from a study using retinal analogs.

To investigate the shape of the chromophore binding site of pharaonis phoborhodopsin (ppR), ppR-opsin was incubated with five ring-modified retinal analogs: an acyclic retinal, phenylretinal, alpha-retinal, cyclohexylretinal and 5-isopropyl-alpha-retinal. The experimental results were compared with those obtained from bacteriorhodopsin-opsin (bR-opsin) and the same retinal analogs. It was suggested that ring chain conformation is important in affecting the spectral shoulder unique for the absorption spectrum of ppR. The rate of pigment formation depended greatly on the analogs used with the planar analogs showing rapid formation. Thus, we concluded that the space of the retinal binding site of ppR is restricted to the plane of the cyclohexenyl ring of the chromophore, whereas that of bR is less restricted.

Archaeal Proteins↗