Biomedical subjects
Publications and source records attributed to Y Shih.
We report a proof-of-principle experimental demonstration of quantum lithography. Utilizing the entangled nature of a two-photon state, the experimental results have beaten the classical diffraction limit by a factor of 2. This is a quantum mechanical two-photon phenomenon but not a violation of the uncertainty principle.
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We report a quantum teleportation experiment in which nonlinear interactions are used for the Bell state measurements. The experimental results demonstrate the working principle of irreversibly teleporting an unknown arbitrary polarization state from one system to another distant system by disassembling into and then later reconstructing from purely classical information and nonclassical EPR correlations. The distinct feature of this experiment is that all four Bell states can be distinguished in the Bell state measurement. Teleportation of a polarization state can thus occur with certainty in principle.
Microwave-assisted extraction (MAE), was used to extract sunscreen agents from cosmetic products. The extracts were analyzed by liquid chromatography (LC). The present method allows the determination of three sunscreen agents, Eusolex 2292, 4360 and 6300. The precision of the assay at 40 microg/ml of sunscreen agents ranged from 1.5 to 2.2%, and the detection limits were 2.0-4.0 ng/ml.
We report a delayed "choice" quantum eraser experiment of the type proposed by Scully and Druhl (where the "choice" is made randomly by a photon at a beam splitter). The experimental results demonstrate the possibility of delayed determination of particlelike or wavelike behavior via quantum entanglement. The which-path or both-path information of a quantum can be marked or erased by its entangled twin even after the registration of the quantum.
A Nafion-ruthenium oxide pyrochlore chemically modified electrode is used for the determination of caffeine in beverages by square-wave voltammetry. Compared to a bare glassy carbon electrode, the chemically modified electrode exhibits a marked enhancement of the current response. A linear calibration curve is obtained over the 5-200 microns range in 0.05 M HCIO4 solution with a detection limit (3 delta) of 2 micron. The results of 15 successive repetitive measurement-regeneration cycles showed a relative standard deviation of 2.7% for 10 micron caffeine. Thus, the electrode renewal gives a good reproducible surface. Quantitative analysis was performed by the standard addition method for caffeine content in tea, coffee, decaffeinated coffee, and cola beverages.
A new type of liquid chromatographic (LC) dual thin-layer amperometric detector for the simultaneous measurement of trace levels of dopamine and serotonin in microdialysates is described. The concentrations of these analytes in rat dialysates are usually in the sub-nanomolar concentration range (typically, 0.10-5.00 pg in 5-microl dialysates). With this dual electrode, a glass-lined microbore column provides excellent sensitivity, selectivity, and separation. In addition, a three- to five-fold improvement in anodic current or cathodic responses over conventional dual electrodes in microbore LC can be achieved. Due to the irreversible electrochemical properties of some interference peaks, this dual electrode provides reliable measurement of dopamine based on the cathodic signal. The detection limit (signal-to-noise ratio = 3) of this assay is 0.02 pg per injection for dopamine or serotonin. This new dual electrode allows the simultaneous measurements of basal dopamine and serotonin in rat striatum dialysates without the use of re-uptake inhibitors in perfusion medium.
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The simultaneous measurement of homovanillic acid, 3,4-dihydroxyphenylacetic acid, serotonin and 5-hydroxyindoleacetic acid in human plasma by an ultrafiltration and microbore high-performance liquid chromatography-electrochemical detection technique is established. Conventional preparation of blood is very tedious and time-consuming, but isocratic separation of the analytes in plasma ultrafiltrates using a microbore column could be achieved within 10 min. Hence, theoretically, over 140 analyses can be performed in a working day. The detection limit (signal-to-noise ratio = 3) of this method is about 0.1-0.5 pg per injection for all analytes. The required volume of plasma samples can be less than 100 microliters. Hence, blood loss is minimal, especially in repeated blood sampling. This rapid, simple and sensitive method can, therefore, be used as a routine clinical tool in the simultaneous measurement of plasma homovanillic acid, 3,4-dihydroxyphenylacetic acid, serotonin and 5-hydroxyindoleacetic acid.
A dual electrochemical detector with two working electrodes (anode and cathode) suitable for high-performance liquid chromatography with a microbore octadecylsilica column was applied for the simultaneous measurement of norepinephrine, epinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 5-hydroxyindoleacetic acid, 3-methoxytyramine and 5-hydroxytryptamine (serotonin) in mouse brain homogenates. Microbore high-performance liquid chromatography provides very good resolution of these analytes and offers selective detection of biogenic amines and their metabolites on the basis of their retention behaviour and electrochemical reversibility. The large early-eluting peak of brain homogenates was eliminated on cathodic detection, thereby providing reliable measurements of early eluates. The detection limit of this method was ca. 0.2-0.5 pg per injection for all components, at a signal-to-noise ratio of 3. Owing to the high sensitivity, the brain tissue samples could be kept very small (less than 10 mg). Isocratic separation of these analytes was achieved within 15 min; hence over 90 analyses could be performed in a single working day. This simple, efficient and sensitive method can be used as a basic research tool for the assaying of biogenic amines and their metabolites in brain homogenates.
Polyethylene glycolated (pegylated) interleukin-2 (PEG IL-2) was administered as a weekly i.v. bolus to patients with metastatic cancer in a phase-I trial. Efficacy, toxicity and pharmacokinetics have been described previously. To explore mechanism of IL-2 action and discover predictors of efficacy, the levels of several lymphokines were measured in pharmacokinetic serum samples. IL-1 beta and IL-6 were elevated in many patients before PEG IL-2 administration, forming a continuous, log-normal distribution among patients. The levels of the two lymphokines were strongly correlated. However, no significant correlation could be found between these levels, clinical chemistry, or tumor regression seen after PEG IL-2 administration. Three hours after PEG IL-2 administration, IL-1 beta and IL-6 levels, if elevated, fell to normal. In all patients, independent of initial levels, IL-6 and IFN-gamma, but not IL-1 beta, increased 4 to 6 h after the injection and then fell rapidly, even though PEG IL-2 levels were high and often changed only slightly during this period. This suggests an active shut down of lymphokine synthesis, or an increase in elimination rate. After the fourth administration of PEG IL-2, the peak level of IFN-gamma was 2 to 20 times higher than after the first, while the peak level of IL-6 did not change in a consistent direction. Responding patients had typical peak levels of IL-6 and IFN-gamma. Low levels of TNF and IL-4 were occasionally seen before and after PEG IL-2 administration, but no consistent pattern was evident.
Eighteen patients undergoing bench surgery and autotransplantation are reported. The major indications for this procedure are renovascular hypertension and neoplasms affecting either both kidneys or a solitary kidney. The least satisfactory results were obtained when calculus disease was present.
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In order to characterize the uterine progesterone-binding proteins of oestrogen-primed and unprimed, ovariectomized immature and adult golden hamsters, cytosols were incubated with [3H]progesterone and/or other steroids and analyzed by sucrose-glycerol density gradient ultracentrifugation. Progesterone-binding components with sedimentation coefficients of 7S and 4.5S were found in the uterine cytosols, but not in the cytosols from the hypothalamus, pituitary, diaphragm, or small intestine. Oestradiol-17beta markedly elevated the level of 7S uterine receptor and this increase appeared to be due to new receptor synthesis, since actinomycin D and cycloheximide blocked this response. Fifty to 100 mug of oestradiol-17beta per kg body weight was found to promote a maximum increase in the 7S macromolecular component. The 7S receptor showed a tendency to saturate at 1 X 10(-7) M [1,2-3H]progesterone, indicating limited capacity. At a molar ratio of 100:1, unlabeled progesterone competed effectively for 7S and 4,5S [3H]progesterone binding, whereas 5alpha-pregnane-3,20-dione, oestradiol-17beta and testosterone did not. Moreover, [1,2-3H]cortisol and [1,2-3H]corticosterone did not bind to the 7S receptor, implying steroid specificity. CI-628, a non-steroid oestrogen antagonist, completely prevented [6,7-3H]oestradiol-17beta binding to its 8.5S uterine cytosol receptor, but was entirely without effect on 7S and 4.5S [3H]progesterone binding. Pronase, but not DNase or RNase, abolished 7S and 4.5S progesterone binding, suggesting that the binders are at least in part protein. Protamine sulphate and p-hydroxymercuribenzoate also obliterated 7S binding, implying that this receptor may be an acidic protein which contains sulfhydryl groups that are necessary for progesterone binding.
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A rapid, sensitive, and reliable method was developed for the simultaneous determination of magnesium L-ascorbyl-2-phosphate (AS-PM) and kojic acid (KA), commonly using bleaching agents in cosmetic products. The method uses a prepacked C18 microbore column for ion-pair liquid chromatography with photodiode array detection. The eluant is 0.5mM tetrabutylammonium bromide and 0.05M phosphate buffer, pH 5, containing 5% methanol, at a flow rate of 70 microL/min. The determinations of AS-PM and KA were linear in the range of 0.5-1,000 and 0.25-500 ng, respectively. The precision of the assay ranged from 0.31 to 2.19%, and the detection limits (signal-to-noise ratio = 3) were 0.04 and 0.02 ng for AS-PM and KA, respectively.
During the period 1958-1983, 986 outbreaks of botulism occurred in China, affecting 4,377 individuals and resulting in 548 deaths. The initial cases of botulism were found in Xinjiang province, where the incidence was highest. Outbreaks have occurred in all of the northern provinces and in some of the southern provinces of China. The toxin found most frequently in the northwest region of China was type A; in north China, type B; and in the northeast, type E. The most frequently offending food was home-made strong-smelling preserved bean curd, which was implicated in 74% of the outbreaks. The complex clinical manifestations of botulism can be grouped into those affecting the eyes, the mouth, the pharynx, and the skeletal muscles. Following the institution of effective methods of prevention and treatment, epidemics of botulism in China have been controlled and the mortality rate reduced from 41% (1950s) to 7.6% (1983).