Inositolphosphoryl ceramide synthase from yeast.
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4-Chloro-7-nitrobenzofurazan↗
Biomedical subjects
Y Liu
Publications and source records attributed to Y Liu.
Grafting of genetically modified fibroblasts into the injured spinal cord.
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Animals↗
Preparation of high activity whole cell biocatalyst by permeabilization of recombinant flocculent yeast with alcohol.
Flocculent yeast Saccharomyces cerevisiae YF234 (MATa ura3-52 trp1Delta2 his ade 2-1 can1-100 sta1 FLO8) cells overexpressing glyoxalase I and having strong flocculation ability were permeabilized with isopropyl alcohol and ethanol under various conditions. The treatment with 40% isopropyl alcohol significantly improves the initial reaction rates of recombinant flocculent yeast cells. Moreover, the reactivity of permeabilized flocculent yeast cells was similar to that of dispersed cells with EDTA. On the other hand, the flocculation ability of yeast cells was not affected by the treatment with alcohol solutions of various concentrations and treatment time length. Therefore, the recombinant flocculent yeast cells permeabilized with alcohol are very effective whole cell biocatalysts.
Journal Article↗
Phagocytosis of wear debris by osteoblasts affects differentiation and local factor production in a manner dependent on particle composition.
Wear debris is considered to be one of the main factors responsible for aseptic loosening of orthopaedic endoprostheses. Whereas the response of cells in the monocytic lineage to foreign materials has been extensively studied, little is known about cells at the bone formation site. In the present study, we examined the hypothesis that the response of osteoblasts to wear debris depends on the chemical composition of the particles. We produced particles from commercially pure titanium (cpTi), Ti-6Al-4V (Ti-A), and cobalt-chrome (CoCr) and obtained ultrahigh molecular weight polyethylene (UHMWPE; GUR 4150) particles from a commercial source. The equivalent circle diameters of the particles were comparable: 1.0 +/- 0.96 microm for UHMWPE; 0.84 +/- 0.12 microm for cpTi; 1.35 +/- 0.09 microm for Ti-A, and 1.21 +/- 0.16 microm for CoCr. Confluent primary human osteoblasts and MG63 osteoblast-like cells were incubated in the presence of particles for 24 h. Harvested cultures were examined by transmission electron microscopy to determine if the cells had phagocytosed the particles. Particles were found intracellularly, primarily in the cytosol, in both the primary osteoblasts and MG63 cells. The chemical composition of the particles inside the cells was confirmed by energy-dispersive X-ray analysis. Morphologically, both cell types had extensive ruffled cell membranes, less-developed endoplasmic reticulum, swollen mitochondria, and vacuolic inclusions compared with untreated cells. CpTi, Ti-A, and CoCr particles were also added to cultures of MG63 cells to assess their effect on proliferation (cell number) and differentiation (alkaline phosphatase activity), and PGE2 production. All three types of particles had effects on the cells. The effect on cell number was dependent on the chemical composition of the particles; Ti-A and CoCr caused a dose-dependent increase, while cpTi particles had a biphasic effect with a maximal increase in cell number observed at the 1:10 dilution. Alkaline phosphatase specific activity was also affected and cpTi was more inhibitory than Ti-A or CoCr. PGE2 production was increased by all particles, but the magnitude of the effect was particle-dependent: CoCr > cpTi > Ti-A. This study demonstrates clearly that human osteoblast-like cells and MG63 cells can phagocytose small UHMWPE, CoCr, Ti-A, and cpTi particles. Phagocytosis of the particles is correlated with changes in morphology, and analysis of MG63 response shows that cell proliferation, differentiation, and prostanoid production are affected. This may have negative effects on bone formation adjacent to an orthopaedic implant and may initiate or contribute to the cellular events that cause aseptic loosening by inhibiting bone formation. The effects on alkaline phosphatase and PGE2 release are dependent on the chemical composition of the particles, suggesting that both the type and concentration of wear debris at an implant site may be important in determining clinical outcome.
Aged↗
Hidden variables: unstable Abeta chain genes encoding antigen recognition structures in tumor survivors.
Novel single exon genes Abeta4-7 comprising the Abeta6 gene family have been cloned from mouse mutants surviving transplantable metastatic tumors. Their protein coding sequences are similar to H2-Ab cDNA which encodes antigen-binding molecules of antigen presenting cells (APC); their promoters and/or signal sequences are unrelated to Ab sequences but found in other eukaryotic genes. Abeta4(b) protein was demonstrated on macrophages and B cells that are APC. The Abeta6(w302) appears to be an ancient gene ancestral to major histocompatibility complex (MHC) class II beta genes. However, unlike the MHC class II, the Abeta4-7 genes are not involved in skin graft rejection. Despite inbreeding, the Abeta6(w302) locus remains unfixed in several strains of mice. The number of Abeta genes and their alleles varied between individual mice; they do not map into the H2 region but appear to be scattered over the genome. The Abeta6 gene family is molecularly unstable in Abeta6(w302)-positive (but not in Abeta6(w302)-negative) mice which are somatic mosaics for these genes. Biological features of Abeta4-7 genes make them remarkably different from the classical MHC gene system. All available evidence strongly suggests that these genes control susceptibility/resistance to the spread of metastatic tumors.
Animals↗
Unipolar brush cell: a potential feedforward excitatory interneuron of the cerebellum.
Unipolar brush cells are a class of interneurons in the granular layer of the mammalian cerebellum that receives excitatory mossy fiber synaptic input in the form of a giant glutamatergic synapse. Previously, it was shown that the unipolar brush cell axon branches within the granular layer, giving rise to large terminals. Single mossy fiber stimuli evoke a prolonged burst of firing in unipolar brush cells, which would be distributed to postsynaptic targets within the granular layer. Knowledge of the ultrastructure of the unipolar brush cell terminals and of the cellular identity of its postsynaptic targets is required to understand how unipolar brush cells contribute to information processing in the cerebellar circuit. To investigate the unipolar brush cell axon and its targets, unipolar brush cells were patch-clamped in fresh parasagittal slices from rat cerebellar vermis with electrodes filled with Lucifer Yellow and Biocytin, and examined by confocal fluorescence and electron microscopy. Biocytin was localized with diaminobenzidine chromogen or gold-conjugated, silver-intensified avidin. Light microscopic examination revealed a single thin axon emanating from the unipolar brush cell soma that gave rise to 2-3 axon collaterals terminating in mossy fiber-like rosettes in the granular layer, typically within a few hundred microm of the soma. In some cases, axon collaterals crossed the white matter within the same folium before terminating in the adjacent granular layer. Electron microscopic examination of serial ultrathin sections revealed that proximal unipolar brush cell axons and axon collaterals were unmyelinated and devoid of synaptic contacts. However, the rosette-shaped enlargements of each collateral formed the central component of glomeruli where they were surrounded by dendrites of granule cells and/or other unipolar brush cells, with which they formed asymmetric synaptic contacts. A long-latency repetitive burst of polysynaptic activity was observed in granule cells in this cerebellar region following white matter stimulation. The unipolar brush cell axons, therefore, form a system of cortex-intrinsic mossy fibers. The results indicate that synaptic excitation of unipolar brush cells by mossy fibers will drive a large population of granule cells, and thus will contribute a powerful form of distributed excitation within the basic circuit of the cerebellar cortex.
Animals↗
Monocyte chemoattractant protein-1 is a mediator of acute excitotoxic injury in neonatal rat brain.
Monocyte chemoattractant protein-1 is a chemokine with potent monocyte activating and chemotactic effects. Monocyte chemoattractant protein-1 gene and protein expression is rapidly up-regulated in response to a variety of acute and chronic central nervous system disorders. The activation and recruitment of microglia and monocytes into areas of inflammation may play a critical role in the pathogenesis of acute brain injury. Monocyte chemoattractant protein-1 could be a pathophysiologically important mediator of the microglial and monocyte responses in the brain. Using a well-characterized model of acute excitotoxic brain injury in neonatal rats, experiments were designed to evaluate whether monocyte chemoattractant protein-1 plays a role in the progression of tissue damage. Direct co-administration of recombinant monocyte chemoattractant protein-1 with the excitotoxin N-methyl-D-aspartate exacerbated injury, both in the striatum and in the hippocampus, by 55% and 167%, respectively. Complementary experiments to determine the effect of functional inhibition of monocyte chemoattractant protein-1, using an anti-monocyte chemoattractant protein-1-neutralizing antibody, revealed that co-administration of the antibody with N-methyl-D-aspartate attenuated tissue injury in the striatum and hippocampus by 57% and 39%, respectively.Together, these data suggest that monocyte chemoattractant protein-1 is a mediator of acute excitotoxic brain injury in neonatal rats and that inflammatory mechanisms contribute significantly to the pathogenesis of acute neonatal brain injury. Whether chemokines are pathophysiologically relevant mediators of neuronal injury in human neonates remains to be determined.
Acute Disease↗
Roles of mitochondrial ATP-sensitive K channels and PKC in anti-infarct tolerance afforded by adenosine A1 receptor activation.
OBJECTIVES: This study intended to assess the role of mitochondrial ATP-sensitive potassium (mitoK ATP) channels and the sequence of signal transduction with protein kinase C (PKC) and adenosine A1 receptors in rabbits. BACKGROUND: To our knowledge, the link between trigger receptors of preconditioning, PKC and mitoK ATP channels has not been examined in a whole heart model of infarction. METHODS: In the first series of experiments, myocardial infarction was induced in isolated buffer-perfused rabbit hearts by 30-min global ischemia and 2-h reperfusion. Infarct size in the left ventricle was determined by tetrazolium staining and expressed as a percentage of area at risk (i.e., the whole left ventricle) (%IS/AR). In the second series of experiments, mitochondria were isolated from the heart, and their respiratory function was examined using glutamate as a substrate. RESULTS: Pretreatment with R-phenylisopropyladenosine (R-PIA, 1 micromol/liter), an A1-receptor agonist, reduced %IS/AR from 49.8 +/- 6.5% to 13.4 +/- 2.9%. This protection was abolished by calphostin C, a PKC inhibitor, and by 5-hydroxydecanoate (5-HD), a selective inhibitor of mitoK ATP channels. A selective mitoK ATP channel opener, diazoxide (100 micromol/liter), mimicked the effect of R-PIA on infarct size (%IS/AR = 11.6 +/- 4.0%), and this protective effect was also abolished by 5-HD. However, calphostin C failed to block the infarct size-limiting effect of diazoxide. Neither calphostin C nor 5-HD alone modified %IS/AR. State III respiration (QO2) and respiratory control index (RCI) were reduced after 30 min of ischemia (QO2 = 147.3 +/- 5.3 vs. 108.5 +/- 12.3, RCI = 22.3 +/- 1.1 vs. 12.1 +/- 1.8, p < 0.05). This mitochondrial dysfunction was persistent after 10 min of reperfusion (QO2 = 96.1 +/- 15.5, RCI = 9.5 +/- 1.9). Diazoxide significantly attenuated the respiratory dysfunction after 30 min of ischemia (QO2 = 142.8 +/- 9.7, RCI = 16.2 +/- 0.8) and subsequent 10-min reperfusion (QO2 = 135.3 +/- 7.2, RCI = 19.1 +/- 0.8). CONCLUSIONS: These results suggest that mitoK ATP channels are downstream of PKC in the mechanism of infarct-size limitation by A1-receptor activation and that the anti-infarct tolerance afforded by opening of mitoK ATP channels is associated with preservation of mitochondrial function during ischemia/reperfusion.
Adenosine Triphosphate↗
Cephalometric comparisons between Chinese and Caucasian patients with obstructive sleep apnea.
The purpose of this study was to compare two groups of adult men from different ethnic backgrounds and with obstructive sleep apnea; they were selected by matching age, gender, skeletal pattern, body mass index, and respiratory disturbance index. Pretreatment cephalometric radiographs and overnight polysomnograms of 30 Chinese and 43 Caucasian patients with Class II, Division 1 malocclusions were analyzed to investigate if there were craniofacial and upper airway structural differences between the two ethnic groups. The Chinese group, when compared with the group of Caucasian patients, revealed more severe underlying craniofacial skeletal discrepancies with significantly smaller maxilla and mandibles, more severe mandibular retrognathism, proclined lower incisors, increased total and upper facial heights, and steeper and shorter anterior cranial bases. However, no significant differences were found between the two groups in posterior facial height, ratio of upper to lower anterior facial height, and the position of hyoid bone, maxilla, and upper incisors. With regard to soft tissue and upper airway measurements, there were no significant ethnic differences in tongue and soft palate size, vertical length of oropharynx, and anteroposterior dimensions of the upper airway at most of the levels except for a larger super-posterior airway space, a larger nasopharynx and oropharynx cross-sectional area, and a smaller tongue height in the Chinese group. We conclude that there are a number of craniofacial and upper airway structures that differ between the two ethnic groups that may be relevant to the treatment of obstructive sleep apnea in various ethnic groups.
Asian People↗
Disrupted development of the cerebral hemispheres in transgenic mice expressing the mammalian Groucho homologue transducin-like-enhancer of split 1 in postmitotic neurons.
Transducin-like Enhancer of split (TLE) 1 is a mammalian transcriptional corepressor homologous to Drosophila Groucho. In Drosophila, Groucho acts together with bHLH proteins of the Hairy/Enhancer of split (HES) family to negatively regulate neuronal differentiation. Loss of the functions of Groucho or HES proteins results in supernumerary central and peripheral neurons. This suggests that mammalian TLE/Groucho family members may also be involved in the regulation of neuronal differentiation. Consistent with this possibility, TLE1 is expressed in proliferating neural progenitor cells of the central nervous system, but its expression is transiently down-regulated in newly generated postmitotic neurons. Based on these observations, we investigated whether persistent TLE1 expression in postmitotic neurons would perturb the normal course of neuronal development. Transgenic mice were derived in which the human TLE1 gene is regulated by the promoter of the Talpha1 alpha-tubulin gene, which is exclusively expressed in postmitotic neurons. In these mice, constitutive expression of TLE1 inhibits neuronal development in the embryonic forebrain leading to increased apoptosis and neuronal loss in the ventral and dorsal telencephalon. These results provide the first direct evidence that TLE1 is an important negative regulator of postmitotic neuronal differentiation in the mammalian central nervous system.
Animals↗
Relation between green tea consumption and the severity of coronary atherosclerosis among Japanese men and women.
PURPOSE: To examine the relation between green tea consumption and arteriographically determined coronary atherosclerosis. METHODS: Study subjects were 512 patients (302 men and 210 women) aged 30 years or older who underwent coronary arteriography for the first time at four hospitals in Fukuoka City or one hospital in an adjacent city between September 1996 and August 1997. Lifestyle characteristics including green tea consumption were ascertained before arteriography by a questionnaire supported with interview. RESULTS: 117 men (38.7%) and 50 women (23.8%) had significant stenosis of one or more coronary arteries. Green tea consumption tended to be inversely associated with coronary atherosclerosis in men, but not in women. An evident, protective association between green tea and coronary atherosclerosis was observed in a subgroup of 262 men excluding those under dietary or drug treatment for diabetes mellitus. In this subgroup, after adjustment for traditional coronary risk factors and coffee, odds ratios of significant stenosis for consumption of 2-3 cups and 4 or more cups per day were 0.5 (95% confidence interval 0.2-1.2) and 0.4 (0.2-0.9), respectively, as compared with a consumption of one cup per day or less. CONCLUSIONS: The results indicate that green tea may be protective against coronary atherosclerosis at least in men.
Adult↗
Ischemic cardiomyopathy and the cellular renin-angiotensin system.
BACKGROUND: Ischemic cardiomyopathy produced by non-occlusive coronary artery constriction is characterized by left ventricular failure and right ventricular dysfunction, but whether the local renin-angiotensin system (RAS) is implicated in myocyte dysfunction and cell death remains unclear. METHODS: Changes in single-cell mechanics, the localization of the various constituents of RAS in the myocardium, and the effects of angiotensin II (Ang II) stimulation on myocyte performance and cell death were measured. RESULTS: Chronic ischemia is coupled with alterations in the mechanical properties and calcium (Ca2+) transients of the remaining viable myocytes. The abnormalities in myocyte mechanics consist of depression in peak shortening and velocity of shortening. Moreover, peak systolic Ca2+ is significantly decreased in the cells. In vitro stimulation with Ang II ameliorates myocyte function and systolic Ca2+. Additionally, adult myocytes express genes for renin, angiotensinogen, angiotensin-converting enzyme (ACE), and Ang II receptors. Renin, ACE, and Ang II receptors mRNAs increase under the setting of impaired coronary perfusion. Similarly, the percentage of myocytes containing renin, Ang I, and Ang II increases as well. In vitro studies of neonatal and adult ventricular myocytes indicate that Ang II triggers programmed myocyte cell death and this phenomenon is mediated by activation of the AT1 receptor sub-type. Importantly, the AT1-receptor blocker, losartan, completely inhibits apoptosis. CONCLUSIONS: These multiple observations are consistent with the notion that Ang II may exert 3 separate functions on the heart: (1) stimulation of myocyte hypertrophy, (2) amelioration of myocyte contractile performance, and (3) activation of the suicide program of myocytes.
Angiotensin II↗
Novel p19 protein engages IL-12p40 to form a cytokine, IL-23, with biological activities similar as well as distinct from IL-12.
A novel sequence discovered in a computational screen appears distantly related to the p35 subunit of IL-12. This factor, which we term p19, shows no biological activity by itself; instead, it combines with the p40 subunit of IL-12 to form a novel, biologically active, composite cytokine, which we term IL-23. Activated dendritic cells secrete detectable levels of this complex. IL-23 binds to IL-12R beta 1 but fails to engage IL-12R beta 2; nonetheless, IL-23 activates Stat4 in PHA blast T cells. IL-23 induces strong proliferation of mouse memory (CD4(+)CD45Rb(low)) T cells, a unique activity of IL-23 as IL-12 has no effect on this cell population. Similar to IL-12, human IL-23 stimulates IFN-gamma production and proliferation in PHA blast T cells, as well as in CD45RO (memory) T cells.
Amino Acid Sequence↗
Langerin, a novel C-type lectin specific to Langerhans cells, is an endocytic receptor that induces the formation of Birbeck granules.
We have identified a type II Ca2+-dependent lectin displaying mannose-binding specificity, exclusively expressed by Langerhans cells (LC), and named Langerin. LC are uniquely characterized by Birbeck granules (BG), which are organelles consisting of superimposed and zippered membranes. Here, we have shown that Langerin is constitutively associated with BG and that antibody to Langerin is internalized into these structures. Remarkably, transfection of Langerin cDNA into fibroblasts created a compact network of membrane structures with typical features of BG. Langerin is thus a potent inducer of membrane superimposition and zippering leading to BG formation. Our data suggest that induction of BG is a consequence of the antigen-capture function of Langerin, allowing routing into these organelles and providing access to a nonclassical antigen-processing pathway.
Amino Acid Sequence↗
Synthesis and experimental study of through-space hydrogen-fluorine and carbon-fluorine spin-spin coupling in 4,5-substituted 1-acetyl-8-fluoronaphthalenes.
The synthesis and NMR study (1H, 13C, and 19F) of a complete series of 4,5-substituted 1-acetyl-8-fluoronaphthalenes are reported. This data revealed a 6J(H,F) and a 5J(C,F) through space coupling between the fluorine and the methyl on the acetyl group (1H and 13C). The magnitude of this coupling constant changes depending on the nature of the substituent at C-4, the internuclear distance, and the solvent.
Carbon↗
Preparation of high-activity whole cell biocatalysts by permeabilization of recombinant yeasts with alcohol.
Recombinant yeast cells intracellularly overexpressing three different enzymes were permeabilized with alcohol under various conditions. The effects of enzyme stability in alcohol and enzyme molecular weight on the activities of permeabilized cells and enzyme leakage during incubation were examined. Saccharomyces cerevisiae YPH250 overexpressing glyoxalase I (GloI), S. cerevisiae MT8-1 overexpressing isocitrate lyase (ICL), and Pichia pastoris GS115 overexpressing beta-galactosidase (beta-gal) were used as model recombinant yeast systems. In all cases, the percentage of alcohol used for the treatment significantly affected the activity of permeabilized whole cell biocatalysts; cells showed high activity when treated with 40% isopropyl alcohol. The activity of whole cell biocatalysts was also significantly affected by the stability of the enzyme in alcohol solution; permeabilized yeast cells overexpressing ICL, which had low stability, showed rather low activity. Although the enzyme leakage from permeabilized cells was rather low in all cases, the molecular weight of the enzyme appeared to affect the extent of enzyme leakage during incubation. Permeabilized cells of P. pastoris overexpressing beta-gal (540 kDa) retained particularly high activity during incubation and could be used as an immobilized whole cell biocatalysts.
Journal Article↗
A general mixture model approach for mapping quantitative trait loci from diverse cross designs involving multiple inbred lines.
Most current statistical methods developed for mapping quantitative trait loci (QTL) based on inbred line designs apply to crosses from two inbred lines. Analysis of QTL in these crosses is restricted by the parental genetic differences between lines. Crosses from multiple inbred lines or multiple families are common in plant and animal breeding programmes, and can be used to increase the efficiency of a QTL mapping study. A general statistical method using mixture model procedures and the EM algorithm is developed for mapping QTL from various cross designs of multiple inbred lines. The general procedure features three cross design matrices, W, that define the contribution of parental lines to a particular cross and a genetic design matrix, D, that specifies the genetic model used in multiple line crosses. By appropriately specifying W matrices, the statistical method can be applied to various cross designs, such as diallel, factorial, cyclic, parallel or arbitrary-pattern cross designs with two or multiple parental lines. Also, with appropriate specification for the D matrix, the method can be used to analyse different kinds of cross populations, such as F2 backcross, four-way cross and mixed crosses (e.g. combining backcross and F2). Simulation studies were conducted to explore the properties of the method, and confirmed its applicability to diverse experimental designs.
Animals↗
Two-dimensional visible/near-infrared correlation spectroscopy study of thermal treatment of chicken meats.
The thermal treatment of chicken meats was investigated by generalized 2D visible/NIR correlation spectroscopy. Synchronous 2D visible correlation analysis revealed that there are at least two bands around 445 and 560 nm, decreasing in intensity with cooking time. The corresponding asynchronous spectrum indicated that the spectral intensity reduction of the two bands occurs before the intensity variation of the 475, 520, and 585 nm bands. It suggested that the 445 and 560 nm bands be assigned to deoxymyoglobin and oxymyoglobin, respectively, and at least one of the 475, 520, and 585 nm bands assigned to the denatured species (metmyoglobin) of myoglobin. Also, the asynchronous 2D NIR correlation spectrum indicated that C-H fractions are easily oxidized. In addition, strong correlation peaks correlating the bands in the visible, SW-NIR, and NIR spectral regions were observed and discussed.
Animals↗