Biomedical subjects
Publications and source records attributed to S Chu.
The decoction of Tribulus terresteis could significantly inhibit the gluconeogenesis and influence glycometabolism on normal mice. The decoction could also reduce the level of triglyceride and the content of cholesterol in the plasma.
OBJECTIVE: To diagnose zygosity of twins by microsatellite polymorphism. METHODS: One hundred and eighty-four samples, including 69 pairs of twins with the same gender and 6 pairs of twins with different gender were recruited. Seventeen sib pairs were also collected for controls. Nine highly polymorphic microsatellite loci were amplified by polymerase chain reaction (PCR) using fluorescence-labeled primers and the products were sized by automated fragment analysis after electrophoresis and laser detection. Zygosity was diagnosed by comparing the concordance of the genotype of the 9 markers. RESULTS: Sixty-three pairs of monozygotic (MZ) and 12 pairs of dizygotic (DZ) twins were assigned their zygosity by comparison of polymorphism of 9 microsatellite loci. Within each of the 63 monozygotic (MZ) pairs there was complete concordance. However, within each of the 12 dizygotic pairs and other 17 sib pairs, discordant loci were found. With five or six markers, the probability that any twin pair was MZ if all markers were concordant was 99% or 99.6%, respectively. With all the nine markers, the probability that any twin pair was MZ if all markers were concordant was 99.95%. CONCLUSION: The technology of gene scan and genotyping provides a rapid and reliable approach to zygosity detection.
By using titin as a model system, we have demonstrated that fluorescence quenching can be used to study protein folding at the single molecule level. The unfolded titin molecules with multiple dye molecules attached are able to fold to the native state. In the native folded state, the fluorescence from dye molecules is quenched due to the close proximity between the dye molecules. Unfolding of the titin leads to a dramatic increase in the fluorescence intensity. Such a change makes the folded and unfolded states of a single titin molecule clearly distinguishable and allows us to measure the folding dynamics of individual titin molecules in real time. We have also shown that fluorescence quenching can signal folding and unfolding of a small protein with only one immunoglobulin domain.
The simple and sensitive in vitro MCF-7 human breast cancer cell proliferation assay was used to examine the proliferation abilities of two Chinese commercial polychlorinated biphenyl (PCB) mixtures made in the 1960s. Chinese PCB3 and Chinese PCB5 were compared with 17 beta-estradiol (E2). All of the positive activities of these types of Chinese PCBs were significantly different compared to controls with respect to MCF-7 cell doubling time. At lower levels of 7.8 pg/ml and 182 pg/ml, the Chinese PCB3 showed 94% and 86% of relative proliferation effects compared to 17 beta-estradiol, respectively. Chinese PCB5, also showed higher cell proliferation activity at lower level of 8.3 pg/ml, with relative proliferation effect as high as 107% in comparison to 17 beta-estradiol. Thus, both PCBs seem to be different from corresponding Aroclor mixtures. However, Chinese PCBs did not express cell proliferation effects at higher levels of 9.1 ng/ml for Chinese PCB3 and 166 pg/ml and 8.3 ng/ml for Chinese PCB3. This may be due to cytotoxicity and/or antiestrogenic compounds in the mixtures.
We measure high-resolution Feshbach resonance spectra for ultracold cesium atoms colliding in different hyperfine and magnetic sublevels. More than 25 resonances are observed for magnetic fields up to 230 G and their positions are measured with an accuracy down to 0.03 G. From these spectra several ground-state molecular interaction parameters can be extracted with sufficient accuracy to permit for the first time an unambiguous and accurate determination of cesium's ultracold collision properties [P. J. Leo, C. J. Williams, and P. S. Julienne, following Letter, Phys. Rev. Lett. 85, 2721 (2000)].
The microscopic and macroscopic response of a polymer solution in start-up shear flow was investigated using fluorescence microscopy of single molecules, bulk viscosity measurements, and Brownian dynamics simulations. An overshoot in viscosity was observed upon flow inception and understood via the observed molecular extension and by simulation findings. Increasing the polymer concentration up to six times the overlap concentration ( C(*)) has no effect on the character of the dynamics of individual molecules.
6-Nitroquipazine has been known as one of the most potent and selective inhibitors of serotonin transporter in vitro and in vivo. Nine derivatives of 6-nitroquipazine were synthesized and tested for their potential abilities to displace [3H]citalopram binding to the rat cortical membranes.
Using fluorescence microscopy, we studied the catalysis by and folding of individual Tetrahymena thermophila ribozyme molecules. The dye-labeled and surface-immobilized ribozymes used were shown to be functionally indistinguishable from the unmodified free ribozyme in solution. A reversible local folding step in which a duplex docks and undocks from the ribozyme core was observed directly in single-molecule time trajectories, allowing the determination of the rate constants and characterization of the transition state. A rarely populated docked state, not measurable by ensemble methods, was observed. In the overall folding process, intermediate folding states and multiple folding pathways were observed. In addition to observing previously established folding pathways, a pathway with an observed folding rate constant of 1 per second was discovered. These results establish single-molecule fluorescence as a powerful tool for examining RNA folding.
The autobiographical memory bump is an increase in the frequency of reported autobiographical memories (AMs) from a particular age range, and has been reported by numerous investigators (for reviews, see Conway, M. A. & Rubin, D. C. (1993). The structure of autobiographical memory. In A. F. Collins, S. E. Gathercole, M. A. Conway & P. E. Morris, Theories of memory. Hove: Lawrence Erlbaum; Rubin, D. C., Rahhal, T. A. & Poon, L. W. (1998). Things learned in early adulthood are remembered best. Memory and Cognition, 26, 3-19) to occur in the second and third decades of life. Invariably, word labels have been used as AM cues but, given that a popular interpretation of the anecdotal 'Proust phenomenon' is that odours evoke AMs which are especially aged, we wondered if a different pattern in the AM bump might emerge if AMs were cued by odours rather than labels. Here we report an attempt to substantiate this aspect of the 'Proust phenomenon' by comparing the distributions of memories across the lifespan when cued by odour and label. Data showed that, in line with previous studies, the bump for label cues was found to peak between ages 11 and 25 years and was confirmed to be quadratic in form. In contrast, the odour-cued memory distribution peaked at 6-10 years and decreased linearly thereafter. In the earliest age interval, 6-10 years, the proportion of AMs retrieved in response to odour cues was significantly greater than that for the label cues. These results provide empirical support for the Proust phenomenon, and have more general implications for the structure and age distribution of stored AMs.
We point out a laser cooling method for atoms, molecules, or ions at low saturation and large detuning from the particles' resonances. The moving particle modifies the field inside a cavity with a time delay characteristic of the cavity linewidth, while the field acts on the particle via the light shift. The dissipative mechanism can be interpreted as Doppler cooling based on preferential scattering rather than preferential absorption. It depends on particle properties only through the coherent scattering rate, opening new possibilities for optically cooling molecules or interacting atoms.
The tub gene is a member of a small, well conserved neuronal gene family of unknown function. Mutations within this gene lead to early-onset blindness and deafness, as well as late-onset obesity and insulin resistance. To test the hypothesis that mutations within other members of this gene family would lead to similar phenotypes as observed in tubby mice, and hence have similar functional properties, we have generated null mutants of the tubby-like protein ( Tulp ) 1 gene by homologous recombination. Similarly to tubby mice, Tulp1 (-/-)mice exhibit an early-onset retinal degeneration with a progressive, rapid loss of photoreceptors, further supporting the notion that previously identified mutations within the human TULP1 gene are indeed causative of retinitis pigmentosa. However, in contrast to tubby mice, Tulp1 (-/-)mice exhibited normal hearing ability and, surprisingly, normal body weight despite the fact that both TUB and TULP1 are expressed in the same neurons within the hypothalamus in areas known to be involved in feeding behavior and energy homeo stasis. However, TUB and TULP1 show a distinctly different staining pattern in the nucleus of these neurons, perhaps explaining the difference in body weight between the Tulp1 (-/-)and tubby mutant mice.
We demonstrate a simple, general purpose method to cool neutral atoms. A sample containing 3x10(8) cesium atoms prepared in a magneto-optical trap is cooled and simultaneously spin polarized in 10 ms at a density of 1.1x10(11) cm (-3) to a phase space density nlambda(3)(dB) = 1/500, which is almost 3 orders of magnitude higher than attainable in free space with optical molasses. The technique is based on 3D degenerate Raman sideband cooling in optical lattices and remains efficient even at densities where the mean lattice site occupation is close to unity.
Human Peroxisome Proliferator-Activated Receptor gamma (PPARgamma) was originally cloned from a human bone marrow library. What role does this ligand activated transcription factor play in hematopoiesis and the immune system? We note that: a) PPARgamma has potential to interact/interfere or synergize with retinoid biology, b) fatty acids and a prostaglandin have been identified as ligands, and c) lymphocytes, monocytes and neutrophils use fatty acids as a major source of energy production, d) PPARgamma has been shown to oppose TNFalpha and down regulate cytokine production in monocytes. Therefore, we undertook a review of the literature and an expression survey of PPARgamma in a number of major organs and cells involved in the hematopoietic system, for the purpose of building a database towards understanding the role and function of PPARgamma gene regulation in the developing blood and immune systems. PPARgamma is expressed before mesodermal induction in tissue in and around Speymann's organizer in the xenopus blastocyst, in erythroid precursors of blood islands and in the circulation of the day 10.0 murine embryo, in human 19 week fetal liver, in some but not all murine and human bone marrow erythroid, myeloid, and monocytoid progenitors, bone marrow stromal cells and adipocytes, osteoblasts, endothelial cells, some T, and B lymphocytes, monocytes, macrophages, and other monocytic derivatives. It can be found in the cells of Peyer's patches, lymphoid follicles, spleen, and thymus. It is not clear if it is ever or transiently expressed in megakaryocytes, mast cells, or neutrophils. Based on the above data and a review of the literature, PPARgamma seems to play a role during the elicitation of immune responses. We propose PPARgamma may be involved in changes in energy states required during activation and development of many cell types involved, and has additional immunologically relevant effects in erythroid, myeloid, monocytic, T and B lymphocytic, stromal, and endothelial cell function.
Spontaneous subcutaneous emphysema is a rare and usually benign entity that may occasionally be symptomatic. We report a case of a patient with advanced cancer who developed extensive but asymptomatic subcutaneous emphysema shortly before death. Perforation of the lower gastrointestinal tract, perhaps as a result of straining due to severe unrelieved constipation or due to fistula formation, is suspected to have been the mechanism. The causes, treatment, and implications for management of this condition are discussed.
Modern health care institutions are often multi-site organisations that implement heterogeneous information management systems interacting with distributed databases. Advances in treatment modality/technology and rapidly changing information technology create increasing demand for changes/redevelopment of many health information applications. These features spawn the need for solutions to (a) guarantee data exchange across different types of applications and database management systems, and (b) reduce the costs of systems development and modification. This paper explores the concept of 'middleware services' as a solution to achieve these goals. It reports on the successful application of a component-based 3-tier system architecture to develop a computerised clinical pathways management system. The implementation experience confirms a number of significant benefits of the 3-tier structure including, reusability, flexibility, significant reduction in costs and efforts of systems development, and provision of easy, open migration pathway for future change of technology and system redevelopment.
The purpose of this study was to investigate dentoalveolar compensation in negative overjet cases. Eighty-eight adult females with either skeletal Class I or skeletal Class III jaw relationships were examined. Of the total, 44 cases showed anterior crossbite and the remaining 44 cases had normal incisor relationships. Four cephalometric parameters were measured: the sagittal jaw relationship, maxillary and mandibular incisor inclination, and the occlusal plane angulation. In the negative overjet cases, correlation analysis was performed between the skeletal and dental measurements. Stepwise discriminate analysis was carried out to separate the negative and normal overjet cases. Compensatory changes for sagittal jaw discrepancies in the negative overjet cases were statistically confirmed for both incisor inclination and occlusal plane angulation. However, the compensatory effects were weaker than in the normal overjet cases. The discriminate analysis successfully separated the normal and negative overjet cases, suggesting that negative overjet results from insufficient dentoalveolar compensation for variations in the sagittal jaw relationships.
Folk wisdom dictates that odours are especially powerful reminders of autobiographical experience, an effect which has become known as the Proust phenomenon. This paper reviews the relevant literature to determine whether there is any substantive evidence to support this view. Different methodologies have been adopted in addressing this issue, but the most revealing and ecologically valid have been the few studies which have examined naturally formed autobiographical memories. From these data, there is at least preliminary evidence that olfactory stimuli can cue autobiographical memories more effectively than cues from other sensory modalities. Explanations for these effects can be invoked from accepted principles in contemporary cognitive psychology.
In the colonic mucosa, short-chain fatty acids change intracellular pH (pH(i)) and extracellular pH (pH(e)). In this report, confocal microscopy and dual-emission ratio imaging of carboxyseminaphthorhodofluor-1 were used for direct evaluation of pH(i) and pH(e) in a simple model epithelium, HT29-C1 cells. Live cell imaging along the apical-to-basal axis of filter-grown cells allowed simultaneous measurement of pH in the aqueous environment near the apical membrane, the lateral membrane, and the basal membrane. Subapical cytoplasm reported the largest changes in pH(i) after isosmotic addition of 130 mM propionate or 30 mM NH(4)Cl. In resting cells and cells with an imposed acid load, lateral membranes had pH(i) values intermediate between the relatively acidic subapical region (pH 6.3-6.9) and the relatively alkaline basal pole of the cells (pH 7.4-7.1). Transcellular pH(i) gradients were diminished or eliminated during an induced alkaline load. Propionate differentially altered pH(e) near the apical membrane, in lateral intracellular spaces between adjacent cells, and near the basal membrane. Luminal or serosal propionate caused alkalinization of the cis compartment (where propionate was added) but acidification of the trans compartment only in response to luminal propionate. Addition of NH(4)Cl produced qualitatively opposite pH(e) excursions. The microscopic values of pH(i) and pH(e) can explain a portion of the selective activation of polarized Na/H exchangers observed in HT29-C1 cells in the presence of transepithelial propionate gradients.