Somatic cell mapping of the adenine nucleotide translocator gene family in cattle.
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Animals↗
Biomedical subjects
L Li
Publications and source records attributed to L Li.
Physical and genetic mapping of the prosaposin gene (PSAP) to bovine chromosome 28.
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Animals↗
Molecular analyses of the sediment of the 11,000-m deep Mariana Trench.
We have obtained sediment samples from the world's deepest sea-bottom, the Mariana Trench challenger point at a depth of 10,898 m, using the new unmanned submersible Kaiko. DNA was extracted from the sediment, and DNA fragments encoding several prokaryotic ribosomal RNA small-subunit sequences and pressure-regulated gene clusters, typically identified in deep-sea adapted bacteria, were amplified by the polymerase chain reaction. From the sequencing results, at least two kinds of bacterial 16S rRNAs closely related to those of the genus Pseudomonas and deep-sea adapted marine bacteria, and archaeal 16S rRNAs related to that of a planktonic marine archaeon were identified. The sequences of the amplified pressure-regulated clusters were more similar to those of deep-sea barophilic bacteria than those of barotolerant bacteria. These results suggest that deep-sea adapted barophilic bacteria, planktonic marine archaea, and some of the world's most widespread bacteria (the genus Pseudomonas) coexist on the world's deepest sea-bottom.
Base Sequence↗
A denitrifying bacterium from the deep sea at 11,000-m depth.
The denitrifying bacterium strain MT-1 was isolated from the mud of the Mariana Trench. The optimal temperature and pressure for growth of this bacterium were found to be 30 degrees C and 0.1 MPa, respectively. However, it showed greater tolerance to low temperature (4 degrees C) and high hydrostatic pressure (50 MPa) as compared with denitrifiers obtained from land. From the results, it can be said that this organism is adapted to the environment of the deep sea. Strain MT-1 was shown to belong to the genus Pseudomonas by analysis of its 16S rDNA. The cytochrome contents of the bacterium were similar to those of Ps. stutzeri in spectrophotometric studies.
Cytochromes↗
Effects of lipid headgroup and packing stress on poly(ethylene glycol)-induced phospholipid vesicle aggregation and fusion.
The effect of lipid headgroup and curvature-related acyl packing stress on PEG-induced phospholipid vesicle aggregation and fusion were studied by measuring vesicle and aggregate sizes using the quasi-elastic light scattering and fluorescence energy transfer techniques. The effect of the lipid headgroup was monitored by varying the relative phosphatidylcholine (PC) and phosphatidylethanolamine (PE) contents in the vesicles, and the influence of hydrocarbon chain packing stress was controlled either by the relative amount of PE and PC content in the vesicles, or by the degree of unsaturation of the acyl chains of a series of PEs, e.g., dilinoleoylphosphatidylethanolamine (dilin-PE), lysophosphatidylethanolamine (lyso-PE), and transacylated egg phosphatidylethanolamine (TPE). The PEG threshold for aggregation depends only weakly on the headgroup composition of vesicles. However, in addition to the lipid headgroup, the curvature stress of the monolayer that forms the vesicle walls plays a very important role in fusion. Highly stressed vesicles, i.e., vesicles containing PE with highly unsaturated chains, need less PEG to induce fusion. This finding applies to the fusion of both small unilamellar vesicles and large unilamellar vesicles. The effect of electrostatic charge on vesicle aggregation and fusion were studied by changing the pH of the vesicle suspension media. At pH 9, when PE headgroups are weakly charged, increasing electrostatic repulsion between headgroups on the same bilayer surface reduces curvature stress, whereas increasing electrostatic repulsion between apposing bilayer headgroups hinders intervesicle approach, both of which inhibit aggregation and fusion, as expected.
Acylation↗
Prediction of solution structures of the Ca2+-bound gamma-carboxyglutamic acid domains of protein S and homolog growth arrest specific protein 6: use of the particle mesh Ewald method.
The solution structures of the N-terminal domains of protein S, a plasma vitamin K-dependent glycoprotein, and its homolog growth arrest specific protein 6 (Gas6) were predicted by molecular dynamics computer simulations. The initial structures were based on the x-ray crystallographic structure of the corresponding region of bovine prothrombin fragment 1. The subsequent molecular dynamics trajectories were calculated using the second-generation AMBER force field. The long-range electrostatic forces were evaluated by the particle mesh Ewald method. The structures that stabilized over a 400-ps time interval were compared with the corresponding region of the simulated solution structure of bovine prothrombin fragment 1. Structural properties of the gamma-carboxyglutamic acid (Gla) domains obtained from simulations and calcium binding were found to be conserved for all three proteins. Analysis of the predicted solution structure of the Gla domain of Gas6 suggests that this domain should bind with negatively charged phospholipid surfaces analogous to bovine prothrombin fragment 1 and protein S.
1-Carboxyglutamic Acid↗
Alteration in the organ distribution of iron by truncated transferrin: implications for iron chelation therapy.
The ability of the partial molecule of transferrin, truncated transferrin (t-Tf), to act as an excretable biologic iron chelator was examined. We confirmed the observations of Zak and Aisen (Zak O, Aisen P. Biochem Biophys Acta 1985;1952:24-8) that thermolysin treatment of human transferrin produces half molecules that retain iron-binding capacity. These molecules are poorly recognized by surface receptors on either human or murine cells. Although the plasma half-life of human transferrin in mice is moderately long (40 hours), injection of t-Tf into mice results in its rapid clearance (half-life = 10 minutes). Injection of iron 59-labeled transferrin results in the deposition of iron in the major hematopoetic organs of mice such as the spleen, bone marrow, and liver. Injection of 59Fe-labeled t-Tf results in the quantitative recovery of iron in the kidneys: 59Fe is retained in the kidney for substantial periods of time with little evidence of its excretion into urine. Injection of iodine 125-labeled t-Tf also results in the deposition of radioactivity in the kidneys, but 125I is rapidly excreted into the urine, where it is detected as free iodine. These results indicate that although t-Tf is directed to the kidney and filtered by the glomerulus, the molecule is reabsorbed and degraded, and iron is retained. These results have implications in the design of iron chelators.
Animals↗
Bradykinin, lemakalim and sodium nitroprusside relax the mouse trachea in vitro by different mechanisms.
The role of K+ channels in the relaxations induced by bradykinin, lemakalim, an activator of ATP-sensitive K+ channels and sodium nitroprusside (SNP), a nitric oxide (NO) donor was examined in the isolated mouse trachea precontracted by methacholine (1 microM). 4-aminopyridine (4-AP, 0.1-2 mM), an inhibitor of 4-AP sensitive delayed rectifier channels, did not alter relaxations induced by bradykinin, lemakalim or SNP. Glibenclamide and glipizide (10-33 microM), inhibitors of ATP-sensitive K+ channels, inhibited relaxation to lemakalim without affecting responses to bradykinin and SNP. Charybdotoxin (10-100 nM) and iberiotoxin (10-100 nM), inhibitors of large conductance Ca2+-activated K+ channels, failed to inhibit relaxation to bradykinin, lemakalim or SNP. Apamin (0.1-1 microM), an inhibitor of small conductance Ca2+-activated K+ channels, did not alter responses to bradykinin, lemakalim and SNP. The results implicate that the mechanism of relaxation induced by bradykinin and SNP is different from that of lemakalim. Relaxation of the isolated mouse trachea by lemakalim appears to be mediated by ATP-sensitive K+ channels. Bradykinin and SNP induced relaxations are not mediated via Ca2+-activated K+ channels.
Animals↗
Two sources of inhibition affecting binaural evoked responses in the rat's inferior colliculus: the dorsal nucleus of the lateral lemniscus and the superior olivary complex.
The present study was undertaken to determine the influence of two extrinsic sources of inhibition on auditory binaural evoked responses recorded from the rat's inferior colliculus. The first source, the dorsal nucleus of the lateral lemniscus (DNLL), is predominantly GABAergic and has both ipsi- and contralateral projections to the central nucleus of the inferior colliculus (ICC). The second, the superior olivary complex (SOC), has a large glycinergic projection from the lateral superior olive (LSO) to the ipsilateral ICC. Thus, both structures are candidates for imposing an inhibitory effect on responses in the ICC. Neural activity was experimentally blocked by local injection of the excitatory amino acids antagonist, kynurenic acid (KYNA), into either DNLL or SOC. Binaural evoked responses were recorded from the ICC as the intensity of the sound in the ipsilateral ear was increased. Interaural intensity difference functions based on the amplitude of the evoked responses were generated before and after the KYNA injection. An injection into the contralateral DNLL greatly reduced the response suppression produced by stimulation of the ipsilateral ear. Injection into the ipsilateral DNLL, however, had no effect. Injection into the ipsilateral SOC reduced the amount of binaural suppression but the effect was apparent only in cases with surgical transection of the contralateral lateral lemniscus at a level below the DNLL. These data support the conclusion that binaural responses in the rat's ICC are shaped by inhibitory projections from both contralateral DNLL and ipsilateral SOC.
Acoustic Stimulation↗
A study on the stability of bronopol in bronopol lotion by ion-paired reversed-phase high performance liquid chromatography.
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Anti-Infective Agents, Local↗
Morphological evidence for supporting cell to hair cell conversion in the mammalian utricular macula.
The possible origin of the immature hair cells that appear in the utricular maculae of guinea pigs following gentamicin-induced hair cell death was investigated. Guinea pigs were continuously infused with bromodeoxyuridine, to label proliferating cells and their progeny, for 2 weeks after inducing damage to the inner ear on one side with gentamicin. The opposite ear in each animal served as control. Serial sections were cut through the entire utricular maculae of both ears of each animal and the number of labelled cells in the epithelium and underlying connective tissue was counted. Label was present in cells in the sensory epithelium in the utricles from the drug exposed ears but not in the controls. The nuclei of cells in the underlying connective tissue were also labelled in both ears. Some of the labelled nuclei in the epithelium were at the level normally occupied by hair cells, but most were at the level of supporting cell nuclei. However, the total number of labelled nuclei in the sensory epithelium was small; the maximum was 12 in one animal. The number of labelled nuclei in the connective tissue of the treated ears was significantly greater than the number in the untreated ear. This confirms that cell proliferation is stimulated in the mature mammalian utricular macula after hair cell loss, but the extent to which it occurs appears to be insufficient to explain the recovery in hair cell numbers which is observed. Detailed thin section studies of the utricular maculae of gentamicin-treated animals over a prolonged post-treatment period were also performed. In utricles which had suffered damage, there were cells which, like supporting cells but unlike hair cells, were resting on basement membrane, but which possessed at their apical ends organized bundles of microvilli similar to immature hair cell stereocilia. Other cells with more obvious stereocilia remained in contact with the basement membrane via and a small feet process. In still other cells, where a stereociliary bundle was obvious and almost mature in appearance, there was a foot process extending towards the basement membrane but not quite in contact, suggesting it had just detached. All these cells were contacted by nerve endings and specialization of the membranes were apparent at the site of cell-neurone contact. The morphological characteristics of these cells are consistent with phenotypic conversion of supporting cells into hair cells and this may account for some of the hair cell production in the mature mammalian vestibular sensory epithelia after hair cell death.
Animals↗
Topical liposome delivery of molecules to hair follicles in mice.
The hair cycle consisting of growing and resting phases, is subject to widespread disease such as androgenic alopecia or loss of pigment which are in need of effective, targeted therapeutics. In order to develop a hair-follicle delivery system we demonstrate here that phosphatidylcholine liposomes entrapping either the fluorescent dye calcein or the pigment melanin can deliver these molecules into the hair follicle and hair shafts of mice when applied topically. Liposomal delivery of these molecules is time dependent. Negligible amounts of delivered molecules enter the dermis, epidermis or blood stream thereby demonstrating the enrichment of follicle delivery. Naked calcein and melanin are trapped in the stratum corneum and are unable to enter the follicle. The potential of the hair-follicle liposome delivery system for therapeutic use for hair disease is discussed.
Administration, Topical↗
Dynamic nuclear polarization of nitrogen-15 in benzamide.
A 15N dynamic nuclear polarization (DNP) experiment is reported in which a 15N DNP enhancement factor of approximately 2.6 x 10(2) is obtained on free radical doped samples of 99% 15N labeled benzamide. The free radicals BDPA (1:1 complex of alpha, gamma-bisdiphenylene-beta-phenylallyl with benzene) and DPPH (2,2-Di(4-tert-octylphenyl)-1-picrylhydrazyl) are used as dopants and the spin relaxation effects of adding these dopants are studied by means of changes in proton and nitrogen T1 values of the samples. The combination in solids of a very low natural abundance, 0.37%, a small gyromagnetic ratio, and a long spin-lattice relaxation time for 15N nuclei create severe sensitivity problems that, in large part, are ameliorated by the signal enhancement observed in the 15N DNP experiment on samples containing free electrons.
Benzamides↗
Measurement of spin-lattice relaxation times of 13C in organic solids.
A transient nuclear Overhauser effect (NOE) makes measurements of the 13C spin-lattice relaxation times in organic solids complicated. Extended Solomon equations are applied in order to describe 13C spin-lattice relaxation with 1H r.f. field irradiation. Spin-lattice relaxation under r.f. irradiation is shown to be generally a triple-exponential process, but it can be reduced to be single-exponential under stronger r.f. field irradiation as well as in the absence of 1H initial magnetizations. Based on numerical calculations, the difference between spin-lattice relaxation curves obeying T1C < T1H and those obeying T1C > T1H is clearly indicated. The methyl group resonances in solid-state L-valine are examined, and the experimental results agree well with the theoretical results.
Carbon Isotopes↗
Multianalyte biosensors on optical imaging bundles.
We present an optical biosensor design that expands the utility of enzyme biosensors. These biosensors are fabricated by site-selective photodeposition of analyte-sensitive polymer matrices on optical imaging fibres. These dual-analyte arrays allow for the simultaneous, independent measurement of the analyte of interest and the transducing analyte. The first integrated optical-biosensors using this design have been prepared that allow both the dependent and independent analytes to be measured simultaneously, for example penicillin and pH (Healey & Walt, 1995) or glucose and O2 (Li & Walt, 1995). Independent measurement of the transducing analyte allows penicillin or glucose to be quantitated in the presence of a concurrent pH or O2 change, respectively. Penicillin can be measured in the range 0.25-10.0 mM in the pH range 6.2-7.5. Glucose can be measured in the range 0.6-20.0 mM in the O2 range 20-100%. The utility of the sensor design was demonstrated by using the penicillin-dual-analyte biosensor to quantitate penicillin produced during a Penicillium chrysogenum fermentation.
Biosensing Techniques↗
The role of natural anti-Gal alpha 1-3Gal antibodies in hyperacute rejection of pig-to-baboon cardiac xenotransplants.
Xenoreactive natural antibodies in humans and higher primates are directed predominantly at Gal alpha 1-3Gal. These antibodies are thought to initiate hyperacute rejection of porcine organ xenografts. The contribution of anti-Gal alpha 1-3Gal antibodies to the xenoractive natural antibody repertoire and to the initiation of hyperacute rejection was tested in a pig-to-baboon cardiac xenograft model. Anti-Gal alpha 1-3Gal antibodies were depleted from baboons by extracorporeal absorption of anti-Gal alpha 1-3Gal antibodies from plasma using columns with a matrix bearing Gal alpha 1-3Galb1-4GlcNAc. Specific removal of anti-Gal alpha 1-3Gal antibodies was achieved prior to transplantation as demonstrated by immunoassay. Porcine hearts were then transplanted into these baboons and the outcome of the transplants was analysed. Immunofluorescence revealed little deposition of baboon antibodies in the grafts. The porcine hearts did not undergo hyperacute rejection even though complement activity was approximately 90% of baseline at the time of transplantation. These findings demonstrate that anti-Gal alpha 1-3Gal antibodies constitute a major fraction of xenoreactive natural antibodies in primate blood and that these antibodies contribute significantly to the pathogenesis of hyperacute xenograft rejection.
Acute Disease↗
Digital mammography: computer-assisted diagnosis method for mass detection with multiorientation and multiresolution wavelet transforms.
RATIONALE AND OBJECTIVES: The authors evaluated a modular computer-assisted diagnosis (CAD) method for mass detection that uses computation of features in three domains (gray level, morphology, and directional texture). Their objectives were to improve the sensitivity of detection and reduce the false-positive (FP) detection rate. MATERIALS AND METHODS: The directional wavelet transform (DWT) method, which uses both multiorientation and multiresolution wavelet transforms to improve image preprocessing and segmentation of suspicious areas and to extract both morphologic and directional texture features, was evaluated with a previously reported image database containing 50 normal and 45 abnormal digitized screen-film mammograms. The mammograms contained all mass types and included 16 minimal cancers. This method was compared with the Markov random field (MRF) method to avoid issues related to case selection criteria. Free-response receiver operating characteristic curves were compared for both DWT and MRF methods. RESULTS: For the DWT method, the sensitivity was 98% and the FP detection rate was 1.8 FP findings per image. For the MRF method, the sensitivity was 90% and the FP detection rate was 2.0 FP findings per image. CONCLUSION: The CAD method applied to the full mammographic image is automatic and independent of mass type. The segmentation of masses as performed with this method may potentially allow visual interpretation according to American College of Radiology criteria.
Algorithms↗
Alagille syndrome is caused by mutations in human Jagged1, which encodes a ligand for Notch1.
Alagille syndrome is an autosomal dominant disorder characterized by abnormal development of liver, heart, skeleton, eye, face and, less frequently, kidney. Analyses of many patients with cytogenetic deletions or rearrangements have mapped the gene to chromosome 20p12, although deletions are found in a relatively small proportion of patients (< 7%). We have mapped the human Jagged1 gene (JAG1), encoding a ligand for the developmentally important Notch transmembrane receptor, to the Alagille syndrome critical region within 20p12. The Notch intercellular signalling pathway has been shown to mediate cell fate decisions during development in invertebrates and vertebrates. We demonstrate four distinct coding mutations in JAG1 from four Alagille syndrome families, providing evidence that it is the causal gene for Alagille syndrome. All four mutations lie within conserved regions of the gene and cause translational frameshifts, resulting in gross alterations of the protein product Patients with cytogenetically detectable deletions including JAG1 have Alagille syndrome, supporting the hypothesis that haploinsufficiency for this gene is one of the mechanisms causing the Alagille syndrome phenotype.
Alagille Syndrome↗