Synthesis of Heterocyclic and Carbocyclic Compounds via Alkynyl, Allyl, and Propargyl Organometallics of Cyclopentadienyl Iron, Molybdenum, and Tungsten Complexes.
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Journal Article↗
Biomedical subjects
R S Liu
Publications and source records attributed to R S Liu.
Effects of estrogen on cognition, mood, and cerebral blood flow in AD: a controlled study.
OBJECTIVE: To examine the effects of estrogen therapy on cognition, mood, and cerebral blood flow in patients with AD. BACKGROUND: Some studies have suggested estrogen may be effective in the treatment of AD. However, most of these studies were not controlled adequately. METHODS: Fifty female AD patients were recruited in a randomized, double-blind, placebo-controlled 12-week trial. Each member of the estrogen-treated group received conjugated estrogen (Premarin) 1.25 mg/day. The primary outcome measures were the Cognitive Ability Screening Instrument (CASI), Clinical Dementia Rating (CDR), and Clinician Interview-Based Impression of Change (CIBIC-plus). The secondary outcome measures were Behavioral Pathology in Alzheimer's Disease (BEHAVE-AD), Hamilton Anxiety Rating Scale (HARS), Hamilton Depression Rating Scale (HDRS), and 99mTc hexamethylpropylene amine oxime SPECT of the brain. RESULTS: No meaningful differences were found between the outcome measures (CASI, CDR, CIBIC-plus, BEHAVE-AD, HARS, HDRS, and cerebral blood flow) taken from the estrogen-treated group and those from the control group. CONCLUSION: A 1.25-mg/day dose of Premarin administered for 12 consecutive weeks does not produce a meaningful effect on cognitive performance, dementia severity, behavior, mood, and cerebral perfusion in female AD patients. Because estrogen therapy has been suspected of yielding adverse effects, and its therapeutic effectiveness is in doubt, additional evaluation of its role in AD treatment ought to be conducted.
Affect↗
Association between brain size and abstinence from alcohol.
Brain shrinkage with chronic alcoholism is well acknowledged. We have shown, with quantitative analysis of serial scans, an increase in hippocampal, cerebral, and cerebellar volume after abstinence from alcohol.
Alcoholism↗
Whole-body PET with (fluorine-18)-2-deoxyglucose for detecting recurrent primary serous peritoneal carcinoma: An initial report.
OBJECTIVE: Because of the limited sensitivity and specificity of conventional tools such as computerized tomography (CT) or magnetic resonance imaging (MRI) for detecting persistent or recurrent primary serous peritoneal carcinoma (PSPC), a reliable means of diagnosis remains elusive. Positron emission tomography (PET) scanning may offer another approach to this problem. METHODS: A prospective study of three patients requiring surgical exploration for suspected recurrence of PSPC received a whole-body PET (fluorine-18)-2-deoxyglucose (FDG) scanning in a teaching hospital from July 1995 to December 1998. The suspected recurrence was based upon clinical findings including a detailed physical examination, serum CA-125 marker ultrasound, CT, and MRI. Three patients were enrolled in this study. RESULTS: In all three patients, PET images demonstrated increased FDG uptake in a distribution that correlated with surgical-pathologic findings (100%); on the contrary, CT can detect 33.3% of these patients with malignant diseases and MRI can detect two-thirds of cases. Serum CA-125 was also elevated in all three patients, although one patient showed an equivocal elevation of 25.7 IU/ml. CONCLUSIONS: Conventional imaging studies are neither sensitive nor specific for detecting recurrent PSPC. In contrast, besides CA-125, PET might offer a relatively effective tool for detecting recurrent primary serous peritoneal carcinoma. Due to the very small number of patients available in this study, considerable research must be performed to clarify the impact of PET on detecting recurrence of PSPC.
Adult↗
Increased cerebral blood flow in MELAS shown by Tc-99m HMPAO brain SPECT.
We report cerebral SPECT studies on two siblings with the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Tc-99m HMPAO brain SPECT was performed 8, 19 and 30 days after a stroke-like episode in one case and 10 days after a stroke-like episode, 6 h after a partial seizure and as a follow-up study in the other. Increased blood flow was seen in both these patients with stroke-like episodes due to MELAS. The cause of the increased blood flow is uncertain, but it may be related to the decreased pH created by local increase in lactic acid.
Adult↗
Hippocampal and cerebellar volumetry in serially acquired MRI volume scans.
In this work, we describe methodologies for serial volumetric measurements of hippocampi and cerebella. Serial scans were co-registered and intensity matched prior to the volumetric measurements. Manual drawing was used to define the boundaries of the hippocampi. For the cerebellar volumetric measurements, the brain was automatically segmented from the co-registered scans; manual drawing was used to define the boundary between the cerebellum and the cerebrum and brainstem. The operator was blinded to the nature of the subject (patient or normal control) and the chronological order of the scans. The coefficient of reliability of hippocampal volume measurements in a group of 20 controls was 0.078 cm(3) (3.1% of the mean baseline volume); for the cerebellum, the value was 3.8 cm(3) (3.0% of the mean baseline volume). We conclude that the methods presented are valid and that the software provides a useful integrated tool for the quantitative analysis of structural changes in serially acquired volume MRI data in prospective, blinded studies.
Adult↗
Evaluation of equivalent dose to working staff with oxygen-15-water in positron emission tomographic studies.
With its short physical half-life and allowing for higher dosage injections, oxygen-15 labeled water has become increasingly important in many clinical applications. However, the use of oxygen-15 labeled water could potentially result in radiation exposures to working staff exceeding regulatory limits. In this study, thermoluminescent dosimeters (LiF-100H) were attached at various parts of the body to measure the accumulated equivalent doses of a physician and to evaluate the radiation risk to the sensitive organs which could receive as many as 10 intravenous injections of (15)O-water for each subject studied. The results showed that during the injections, the hands of a physician received the highest dose, which was about 25.8 times that of the routine chest X-ray dose. If protective shieldings were provided during injection, about 83% of the dose could be effectively reduced. Even without any protective shielding, the estimated maximum dose to the physician was still within the regulatory limit, 50 mSv/year, suggested by ICRP 60. In conclusion, reducing excess radiation exposure to workers, by minimizing the time spent in close contact with patients, increasing the distance from the source and providing suitable protective shielding would be the most effective approach.
Humans↗
Cerebral blood flow and glucose metabolism in an infant with Sturge-Weber syndrome.
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Brain↗
Comparison of 201Tl SPET and treadmill exercise testing in patients with Kawasaki disease.
About 4% of children with Kawasaki disease ultimately develop ischaemic heart disease. Therefore, the early detection, non-invasive monitoring and long-term follow-up of myocardial ischaemia are essential. We compared the sensitivity and specificity of 201Tl single photon emission tomography (SPET) and treadmill exercise in the detection of myocardial ischaemia in 23 patients (19 boys, 4 girls) with Kawasaki disease. They were divided into two groups according to the results of coronary angiography. Group I consisted of 11 patients with coronary abnormalities; Group II consisted of 12 patients with no coronary abnormalities. The sensitivity, specificity, false-positive and false-negative rates for detecting coronary arterial lesions were 72.7% (8/11), 58.3% (7/12), 38.5% (5/13) and 30% (3/10) for 201Tl SPET, and 45.5% (5/11), 100% (12/12), 0% (0/5) and 33.3% (6/18) for treadmill exercise, respectively. We conclude that 201Tl SPET is more sensitive than treadmill exercise for the detection of coronary arterial abnormalities, but that the specificity of treadmill exercise is better than that of 201Tl scintigraphy. Coronary artery lesions detected by coronary angiography have good concordance of ischaemic areas with perfusion defects detected by 201Tl SPET. When ischaemic findings on 201Tl SPET and/or positive treadmill exercise testing are noted, coronary angiography is strongly indicated to detect possible stenotic lesions in the coronary arteries.
Adolescent↗
Positron emission tomography for the assessment of myocardial viability in Kawasaki disease using different therapies.
13N-ammonia and 18F-fluorodeoxyglucose positron emission tomography (PET) of the heart were performed on 30 children with a history of Kawasaki disease. The results indicated PET abnormalities in 61.1% of patients during the acute and subacute stages and in 41.2% of patients in the convalescent stage of Kawasaki disease. Two-dimensional echocardiography and coronary angiography could not predict the myocardial viability and perfusion as well as PET. Different therapies during the acute stage of the disease did not effectively prevent myocardial damage, despite the absence of coronary arterial abnormalities. The patients who received 400 mg x kg(-1) x day(-1) of intravenous immunoglobulin (IVIG) for 5 days had a significantly lower incidence of PET abnormalities than those who received a single dose of 2000 mg x kg(-1) IVIG (P < 0.05).
Child↗
Robotic synthesis of 6-[18F]fluoro-L-dopa.
The aim of this study was to develop a method of semi-automated 6-[18F]fluoro-L-dopa (6-[18F]FDOPA) synthesis using a robotic system (Scanditronix Anatech RB III, Uppsala, Sweden). [18F]Fluorine was produced via 20Ne(d,alpha)18F using a Scanditronix MC17F cyclotron (Uppsala). The radiosynthesis was performed by the Scanditronix Anatech RB III robotic system. On average, a typical run produced 16-19 mCi of 6-[18F]FDOPA at end of synthesis (EOS) after 2 h irradiation of the F2/neon gas target. The total synthesis time was 110 min. The retention time of 6-[18F]FDOPA (the radio peak) was 8.2 min, which was consistent with the 6-[19F]FDOPA ultraviolet peak. The radiochemical purity was greater than 97%. A robotic, semi-automated method for 6-[18F]FDOPA radiosynthesis is therefore feasible. The radiation burden for the operator can be reduced as much as possible. Sufficient activity of 6-[18F]FDOPA could be obtained for positron emission tomography studies of dopaminergic function.
Dihydroxyphenylalanine↗
Burkitt's lymphoma presenting with jaw lesions.
We report an unusual case of Burkitt's lymphoma (BL) presenting with jaw lesions in a 14-year-old Chinese boy. The patient presented initially with mobile teeth in all 4 jaw quadrants, with corresponding radiographic detection of alveolar bone crest destruction and periapical bone resorption in the absence of clinically detectable jaw tumors. Moreover, radiographs taken only 17 days later showed clearly distinguishable signs of more extensive alveolar bone destruction compared with the initial radiographs.
Adolescent↗
Positron emission tomography scan in cortical visual loss in patients with organophosphate intoxication.
OBJECTIVE: To determine the cerebral metabolism of patients with cortical visual loss. DESIGN: Two observational case studies. TESTING: Two patients who survived acute organophosphate poisoning with respiratory failure experienced severe visual loss despite relatively normal ophthalmic examination results. Magnetic resonance imaging of the brain revealed no abnormality of the visual system in either patient. Positron emission tomography (PET) was performed in these 2 patients and in 12 normal subjects with fluorine-18 fluorodeoxyglucose (FDG) as a tracer to measure cerebral glucose metabolism for the estimation of neurologic deficit in the visual cortex. MAIN OUTCOME MEASURES: The FDG uptake values were measured as nanoCurie per cubic centimeters of tissue (nCi/cc). The relative uptake index in visual cortex was computed as the ratio of uptake of FDG in each region of visual cortex to that of cerebellum (regional visual cortex/cerebellum). RESULTS: Hypometabolism was observed in the visual cortex of both patients. The relative uptake index of FDG in visual cortex (visual cortex/cerebellum) was significantly decreased in those patients compared with normal subjects. CONCLUSIONS: In patients with cortical visual loss, conventional neuroimaging techniques can fail to visualize damage that can be detected by PET scanning, and PET analysis may be helpful in estimating the metabolic deficit of visual cortex and in establishing the organic nature of cortical visual loss in these patients.
Adult↗
11C-acetate clearance in nasopharyngeal carcinoma.
This study assessed 11C-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg-1 body weight of 11C-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of 11C-acetate from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of 11C-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that 11C-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology.
Acetates↗
Evaluation of the dose to the bladder wall using a dynamic balloon-bladder phantom and TLD measurements in 18F-FDG PET studies.
[18F]-2-deoxyglucose (18F-FDG) is one of the most useful radiopharmaceuticals in clinical positron emission tomographic imaging. Its final metabolic destination is the bladder, which accumulates the highest absorbed dose in the body during imaging. The aims of this study were to develop a dynamic bladder phantom to emulate the dynamic response of the bladder and to evaluate changes in the dose to the bladder wall during the imaging procedure. 18F-FDG of various concentrations can be drip-fed intravenously to the balloon-bladder at different uptake phases or extracted from the phantom during voiding. A dose evaluation model, introducing the concept of photon energy flux conversion into the dose calculation, is thus developed for clinical evaluation. The dose to the bladder wall using the proposed model is comparable to that measured using a thermoluminescence dosimeter (TLD), with a less than 5% discrepancy. The main advantages of the model are the use of the dose conversion factor, phi TLD, which is determined from real TLD measurements, and the ability to consider the dynamic characteristics of the bladder. To overcome the problems of diverse dose distributions among subjects, time-activity information provided by clinical bladder imaging is required, so that the method can be applied to other radiopharmaceuticals.
Fluorodeoxyglucose F18↗
Probing for the threshold energy for visual transduction: red-shifted visual pigment analogs from 3-methoxy-3-dehydroretinal and related compounds.
While azulenic retinal analogs failed to yield a red-shifted visual pigment analog, the 9-cis isomers of the push-pull polyenals 3-methoxy-3-dehydroretinal and 14F-3-methoxy-3-dehydroretinal yielded iodopsin pigment analogs with absorption maxima at, respectively, 663 and 720 nm. The former gave a relatively stable batho product (700 nm) and was able to activate transducin. A lower activity was observed for the latter. One possible explanation for the combined results is that the excitation energies of these red-shifted pigments are approaching the threshold energy for visual transduction (although at this time we cannot rigorously exclude a role of the added F-atom in reducing the transducin activity).
Retinal Pigments↗
Whole-body PET with (fluorine-18)-2-deoxyglucose for detecting recurrent ovarian carcinoma. Initial report.
OBJECTIVE: To investigate positron emission tomography (PET) with (fluorine-18)-2-deoxyglucose (FDG) for detecting recurrent ovarian carcinoma. STUDY DESIGN: Wholebody FDG-PET scanning was performed on five patients before surgical exploration. All five patients were suspected of having recurrence based upon clinical findings and underwent surgery after scanning. RESULTS: In all five patients, PET images demonstrated increased FDG uptake in a distribution that correlated with surgical-pathologic findings (100%); computer tomography can detect 60% of such patients with malignant disease. Two cases with unexplained elevated serum CA-125 had lesions localized by PET. CONCLUSION: Recurrence of ovarian carcinoma was clearly imaged with FDG-PET and was confirmed by surgical pathology. FDG-PET might be a fairly effective tool for detecting recurrent ovarian carcinoma.
CA-125 Antigen↗
Posterior 180 degrees 99mTc-dimercaptosuccinic acid renal SPECT.
UNLABELLED: As a result of a high percentage of hypoactive upper poles of kidneys in traditional 99mTc-dimercaptosuccinic acid (DMSA) SPECT, a prospective study was conducted using 180 degrees acquisition technique compared with 360 degrees to minimize tissue attenuation. METHODS: Anterior 180 degrees, posterior 180 degrees and 360 degrees renal SPECT images were obtained simultaneously using a dual-head camera. Forty-one subjects without renal disease and 16 subjects with 21 cortical defects were included in this study. The total counts of the raw data in the anterior 180 degrees, posterior 180 degrees and full 360 degrees were calculated. Small regions of interest were drawn over the cortex of the kidney on coronal and reoriented sagittal slices. Quantitative evaluation of regional activity was performed on the same frames in all three acquisition methods. RESULTS: Comparison of the total renal counts between the anterior and posterior 180 degrees data showed reduced counts in the anterior 180 degrees data collection (P < 0.01). Visual evaluation of the reconstructed images from anterior 180 degrees, posterior 180 degrees and full 360 degrees data collection showed the best image uniformity in the posterior 180 degrees image. The upper/lower pole ratio in the posterior 180 degrees renal SPECT images increased significantly in comparison to full 360 degrees renal SPECT images (P < 0.01) and anterior 180 degrees SPECT images (P < 0.01). The renal defects were more clearly visualized in the posterior 180 degrees renal SPECT images than the full 360 degrees renal SPECT images. The defect/normal cortex ratios in the posterior 180 degrees renal SPECT images were much lower than those from the full 360 degrees SPECT images (P < 0.01) and those from the anterior 180 degrees SPECT images (P < 0.01). CONCLUSION: The posterior 180 degrees acquisition technique can avoid the problem of hypoactive upper pole and can be less time consuming in 99mTc-DMSA SPECT images. It also provides superior lesion contrast in the clinical evaluation of patients with renal scarring.
Child↗