Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Lighting”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1994

Skeletal muscle myosin regulatory light chains conformation affects the papain cleavage of A1 light chains.

In the present study, the influence of magnesium-for-calcium exchange and phosphorylation of regulatory light chain (RLC) on accessibility of myosin and heavy meromyosin alkali light chains (A1) for papain digestion was investigated. The properties of native and papain treated myosin and heavy meromyosin were compared. Exchange of magnesium ions bound to RLCs for calcium ions accelerates the digestion of A1 in the presence of ATP in dephosphorylated myosin, heavy meromyosin, acto-myosin and the acto-heavy meromyosin complex. In the absence of ATP the exchange of magnesium ions bound to RLCs for calcium ions delays the digestion of A1 in the acto-myosin complex. Myosin and heavy meromyosin having shortened A1 by papain cleavage shows decreased K(+)-ATPase and increased actin binding ability in the presence and absence of ATP. The cooperation of RLC and A1 with heavy chains in the changes of structural organization of myosin head during muscle contraction is discussed.

Animals↗
PubMed2002

Proteolytic activity against the light-harvesting complex and the D1/D2 core proteins of Photosystem II in close association to the light-harvesting complex II trimer.

Light-harvesting complex II (LHCII) prepared from isolated thylakoids of either broken or intact chloroplasts by three independent methods, exhibits proteolytic activity against LHCII. This activity is readily detectable upon incubation of these preparations at 37 degrees C (without addition of any chemicals or prior pre-treatment), and can be monitored either by the LHCII immunostain reduction on Western blots or by the Coomassie blue stain reduction in substrate-containing "activity gels". Upon SDS-sucrose density gradient ultracentrifugation of SDS-solubilized thylakoids, a method which succeeds in the separation of the pigment-protein complexes in their trimeric and monomeric forms, the protease activity copurifies with the LHCII trimer, its monomer exhibiting no activity. This LHCII trimer, apart from being "self-digested", also degrades the Photosystem II (PSII) core proteins (D1, D2) when added to an isolated PSII core protein preparation containing the D1/D2 heterodimer. Under our experimental conditions, 50% of LHCII or the D1, D2 proteins are degraded by the LHCII-protease complex within 30 min at 37 degrees C and specific degradation products are observed. The protease is light-inducible during chloroplast biogenesis, stable in low concentrations of SDS, activated by Mg(2+), and inhibited by Zn(2+), Cd(2+), EDTA and p-hydroxy-mercury benzoate (pOHMB), suggesting that it may belong to the cysteine family of proteases. Upon electrophoresis of the LHCII trimer on substrate-containing "activity gels" or normal Laemmli gels, the protease is released from the complex and runs in the upper part of the gel, above the LHCII trimer. A polypeptide of 140 kDa that exhibits proteolytic activity against LHCII, D1 and D2 has been identified as the protease. We believe that this membrane-bound protease is closely associated to the LHCII complex in vivo, as an LHCII-protease complex, its function being the regulation of the PSII unit assembly and/or adaptation.

Centrifugation, Density Gradient↗
PubMed1996

Hereditary polymorphic light eruption of American Indians: occurrence in non-Indians with polymorphic light eruption.

BACKGROUND: Hereditary polymorphic light eruption (HPLE) occurs unique ly in the American Indian and Inuit and exhibits autosomal dominant transmission. Because the cutaneous expression of HPLE resembles that of polymorphic light eruption (PLE) and because many non-Indians in the United States have American Indian heritage, some instances of PLE may actually be HPLE. OBJECTIVE: Our purpose was to determine whether non-Indian patients with PLE have characteristics suggestive of HPLE. METHODS: We surveyed in Nebraska 25 European-Caucasian and 36 African-American patients with PLE for American Indian heritage and photosensitive relatives. Nonphotosensitive subjects (52 Caucasians and 40 African Americans) were surveyed for American Indian heritage. RESULTS: American Indian heritage occurred in 11 Caucasian patients (44%); of those, seven (64%) had photosensitive relatives. Likewise, 29 African Americans (81%) had American Indian heritage; 19 (66%) of those had photosensitive relatives. American Indian heritage occurred in 10 Caucasian control subjects (19%) and in 34 African-American control subjects (85%). CONCLUSION: If American Indian heritage and a family history of photosensitivity are definitive for HPLE, seven (28%) of our Caucasian patients and 19 (53%) of our African-American patients have HPLE rather than PLE. We urge physicians who suspect PLE in non-Indians to ask about American Indian heritage and photosensitive relatives and to screen their present patients with PLE for such characteristics.

Adolescent↗
PubMed2003

Characterization of light gluten and light steep water from a corn wet milling plant.

The primary commodity of corn wet milling is starch, but two coproducts (corn gluten feed, CGF and corn gluten meal, CGM) also are produced. CGM and CGF are marketed as animal foodstuffs and are important economically; however, variation in composition reduces quality. There are few data on the effect of composition of the parent process streams, light steep water (LSW) and light gluten (LG), respectively, on composition of CGF and CGM. The objective was to characterize LG and LSW. Samples of LG and LSW were collected: (1) hourly for one day, (2) every 3 h for 3 days, and (3) daily for 3 weeks. Dry matter, N and ash were determined. Variation in composition of LG and LSW was greatest during longer periods of time (days and weeks) rather than shorter (hourly or every 3 h). There was significant variation in DM (solids) content, which directly affected the concentration of other components. Variation in N (protein) of LG and LSW accounted for much of the variation in CGF and CG. Processes that modify processing and reduce variation could increase the quality of CGF and CGM.

Agriculture↗
PubMed2000

Selective light-induced modulation of bcl-XL and bax expressions in indocyanine green-loaded U937 cells: effects of continuous or intermittent photo-sensitization with low IR-light using a 805-nm diode laser.

The present study is concerned with the effects of an IR diode laser source emitting at 805 nm on a human leukaemic cell strain from a histiocytic lymphoma (U937) pre-loaded with the dye indocyanine green (ICG). The first aim of this work was the assessment of the earliest cellular defense events occurring upon ICG photosensitization. To this purpose, photosensitization was performed at low ICG concentration and low light energy density. The second aim was the comparative evaluation of the effects produced by continuous or fragmented irradiation. Independent of the irradiation method employed (continuous or fragmented), we could demonstrate that cells are forced to apoptosis, as indicated by the appearance in cell extracts of the 85-kDa proteolytic fragment of the poly(ADP-ribose)polymerase (PARP). This proteolysis, however, could be entirely prevented by a specific Caspase-3 inhibitor benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone (Z-DEVD-fmk). Indeed the only perceptible change in the expression of pro/antiapoptotic proteins produced by continuous photostimulation was a small, albeit reproducible, increase in Bax. In contrast, when the photostimulation was achieved by means of several consecutive pulses, we observed not only a remarkable increase in Bax but also a noticeable abatement in Bcl-XL expression. The potential involvement of singlet oxygen in this process has been directly demonstrated by ICG photo-mediated oxidation of dithiothreitol in water. It has also been demonstrated that this oxidation is apparently more efficient when ICG is photostimulated by light pulses.

Apoptosis↗
PubMed2006

Efficient green-blue-light-emitting cationic iridium complex for light-emitting electrochemical cells.

A highly luminescent novel cationic iridium complex [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 was synthesized and characterized using NMR, UV-visible absorption, and emission spectroscopy and electrochemical methods. This complex displays intense photoluminescence maxima in the green-blue region of the visible spectrum and exhibits unprecedented phosphorescence quantum yields, 80 +/- 10% with an excited-state lifetime of 2.2 mus in a dichloromethane solution at 298 K. Single-layer light-emitting electrochemical cells with the charged complex as conducting and electroluminescent material sandwiched between indium-tin oxide and Ag electrodes were fabricated, which emit green-blue light with an onset voltage as low as 2.5 V. Density functional theory calculations were performed to provide insight into the electronic structure of the [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 complex, comparing these results with those obtained for [iridium bis(2-phenylpyridine)(4,4'-tert-butyl-2,2'-bipyridine)]PF6.

Journal Article↗
PubMed2002

Solid-state light-emitting devices based on the tris-chelated ruthenium(II) complex. 4. High-efficiency light-emitting devices based on derivatives of the tris(2,2'-bipyridyl) ruthenium(II) complex.

Light-emitting devices from the tris(2,2'-bipyridyl)ruthenium(II) complex [Ru(bpy)(3)(2+)] and new derivatives thereof were prepared. Due to the electrochemical nature of the device operation, single-layer devices in an ITO/ Ru(bpy)(3)(2+) complex + PMMA/Ag sandwich configuration achieved very high external quantum efficiencies. The derivatives of the Ru(bpy)(3)(2+) complex were designed and synthesized to inhibit self-quenching of the excited state by adding different alkyl substituents on the bipyridyl ligands. As a result, devices that contain these new Ru(bpy)(3)(2+) complexes show a higher photoluminescence and electroluminescence efficiency than devices made from the unmodified Ru(bpy)(3)(2+) complex. External quantum efficiencies up to 5.5% at brightnesses in the range of 10-50 cd/m(2) are reported. In addition, the response time of such devices (which is a result of the electrochemical operation) has been shortened dramatically. An "instantaneous" light emission is achieved for devices that employ smaller counterions such as BF(4)(-) to increase the ionic conductivity. Such a device shows a response time of less than 1 s to emit 10-20 cd/m(2) after the operating voltage of 2.4 V has been applied.

Journal Article↗
PubMed2006

Electronic properties of anthracene derivatives for blue light emitting electroluminescent layers in organic light emitting diodes: a density functional theory study.

Molecular level parameters are investigated computationally to understand the factors that are responsible for the higher efficiency in derivatives of 9,10-bis(1-naphthyl)anthracene (alpha-ADN), 9,10-bis(2-naphthyl)anthracene (beta-ADN), their tetramethyl derivatives (alpha,beta-TMADN) and the t-Bu derivative (beta-TBADN) as blue light emitting electroluminescent (EL) layers in organic light emitting diodes (OLEDs). DFT studies at the B3LYP/6-31G(d,p) level have been carried out on the substituted anthracenes. The absorption spectra are simulated using time dependent DFT methods (TD-DFT) whereas the emission spectra are approximated by optimizing the excited state by HF/CI-Singles and then carrying out the vertical CI calculations by the TD-DFT method. The reorganization energy for estimating the hole and electron transport is calculated. The transfer integrals between parallely stacked molecules in the bulk state are estimated by calculating the electronic splitting. The substituted anthracenes are compared with unsubstituted anthracene and yet untested 9,10-dianthrylanthracene (TANTH). A larger and slower buildup of the electrons and holes in the EL layer, due to the higher reorganization energy and smaller electronic coupling between the adjacent molecules could lead to an increase in hole-electron recombination in the layer and thus increase the efficiency.

Journal Article↗
PubMed2005

Scattering structure factor of colloidal gels characterized by static light scattering, small-angle light scattering, and small-angle neutron scattering measurements.

The scattering structure factor of a colloidal gel in a q range of 5 orders of magnitude has been determined by combining static light scattering, small-angle light scattering, and neutron scattering measurements. It exhibits simultaneously two types of structure information: a mass fractal scaling within the clusters that constitute the gel and a surface fractal scaling for length scales larger than that of the clusters. Such scattering behavior can be well interpreted by the pair-correlation function proposed in the literature to model an ideal structure constituted of mass fractal objects inside surface fractal objects.

Journal Article↗
PubMed2004

Comparison of nanoparticle size and electrophoretic mobility measurements using a carbon-nanotube-based coulter counter, dynamic light scattering, transmission electron microscopy, and phase analysis light scattering.

The precision and accuracy of measurements of the diameter and electrophoretic mobility (mu) of polymeric nanoparticles is compared using four different analytical approaches: carbon-nanotube-based Coulter counting, dynamic light scattering (DLS), transmission electron microscopy (TEM), and phase analysis light scattering (PALS). Carbon-nanotube-based Coulter counters (CNCCs) use a 132 nm diameter channel to simultaneously determine the diameter (28-90 nm) and mu value for individual nanoparticles. These measurements are made without calibration of the CNCC and without labeling the sample. Moreover, because CNCCs measure the properties of individual particles, they provide true averages and polydispersities that are not convoluted into the intrinsic instrumental response function of the CNCC. CNCCs can be used to measure the size of individual nanoparticles dispersed in aqueous solutions, which contrasts with the TEM-measured size of individual dehydrated particles and the ensemble size averages of dispersed particles provided by DLS. CNCCs provide more precise values of mu than PALS.

Journal Article↗
PubMed2004

Light-driven molecular hinge: a new molecular machine showing a light-intensity-dependent photoresponse that utilizes the trans-cis isomerization of azobenzene.

[reaction: see text] A new class of molecular machine exhibits a hingelike motion upon photoirradiation. The motion (close and open) can be operated by alternate irradiation with UV and visible light. The trans/trans and cis/cis isomers are thermally stable at 40 degrees C, and the photochemical closure reaction (from trans/trans to cis/cis isomer) is dependent on the intensity of the light used because of the short-lived intermediate (trans/cis isomer).

Journal Article↗
PubMed2005

Visible light decomposition of ammonia to dinitrogen by a new visible light photocatalytic system composed of sensitizer (Ru(bpy)(3)2+), electron mediator (methylviologen) and electron acceptor (dioxygen).

Visible light decomposition of aqueous ammonia to dinitrogen was successfully achieved by using a new photocatalytic system based on a molecular photoelectron relay composed of a sensitizer (Ru(bpy)(3)2+), an electron mediator (methylviologen) and an electron acceptor (dioxygen), which can be used as a visible light-driven photocatalyst instead of UV-driven semiconductors.

Journal Article↗
PubMed1996

Structural peculiarities of a truncated V kappa III immunoglobulin light chain in myeloma with light chain deposition disease.

We report on the primary sequence of the monoclonal immunoglobulin light chain (LC) REV involved in myeloma-associated light chain deposition disease (LCDD). This sequence was deduced from that of the corresponding complementary (c)DNA in bone marrow plasma cells. Products of three independent amplifications by polymerase chain reaction (PCR) were sequenced and found to be identical. The kappa mRNA encoding this N-glycosylated LC showed an overall normal structure consisting of a V kappa III segment rearranged to J kappa II. Direct N-terminal amino acid sequencing of the circulating monoclonal IgA2, kappa showed identity with the bone marrow-derived sequence. The kappa-chain presented several unusual features affecting both the leader sequence and the variable (V) region. Four unique amino acid substitutions were found at positions -8, -3, -2 and -1 in the leader sequence and probably resulted in an unusual cleavage by signal peptidase, thus making the LC truncated by one residue and accounting for its unique hydrophobic N-terminus: Ile-Ile-Leu. Additional peculiarities were observed in the V region, including a Thr74-->Asn substitution creating a N-glycosylation site, and Thr53-->Ile, which was only reported once among human kappa III chains, in another LCDD case, and may be of special significance at a position usually harbouring a polar amino acid.

Amino Acid Sequence↗
PubMed2003

The effect of exposing murine splenocytes to UVB light, psoralen plus UVA light, or gamma-irradiation on in vitro and in vivo immune responses.

BACKGROUND: WBCs in blood components are a major factor contributing to immune responses such as GVHD and alloimmunization that follow transfusion. Irradiation of blood components has been used to regulate the contribution of donor WBCs to these immune responses. A systematic comparison of how the exposure of lymphoid cells to gamma-irradiation, UVB light, or psoralen + UVA light (PUVA) effects immune response was conducted to better define the best type of irradiation to be used in different clinical settings. STUDY DESIGN AND METHODS: Murine spleen cells were irradiated with varying doses and tested for their in vitro ability to be activated, to proliferate in response to mitogen or allogeneic stimulator cells, or to serve as stimulator cells. Irradiated donor cells were also tested for in vivo generation of GVHD, induction of alloantibody production, induction of restricted cytolytic T lymphocytes, and persistence of irradiated cells. RESULTS: In general, increasing amounts of irradiation resulted in increased inhibition of in vitro and in vivo responses, although the doses required for inhibition differed from assay to assay. In contrast, irradiation of donor cells did not always result in inhibition of recipient alloantibody responses but was dependent on the donor-recipient combination that was studied. CONCLUSION: Control of the in vivo outcomes of transfusing allogeneic cells is regulated by the type and dose of irradiation used and by the genotype of the donor and/or recipient.

Animals↗
PubMed1985

[Critical assessment of light reflection rheography. Comparative studies of phlebodynamometry using invasive measurement of venous pressure, photoplethysmography and light reflection rheography].

In chronic venous insufficiency, phlebodynamometry by invasive venous-pressure measurement demonstrates a reduced pressure drop and an accelerated pressure rise, resulting from the action of the ankle-joint-calf muscle "pump". On the other hand, light-reflexion rheography and photoplethysmography can measure only the duration of the refilling period. Simultaneous measurements were made on 47 legs after phlebography (normal: 8; side-arm varicosities: 17; long-saphenous insufficiency: 15; postthrombotic syndrome: 7). Refilling time by photoplethysmography correlated better with that measured invasively than by light-reflexion rheography. Refilling half-time cannot be measured accurately with either noninvasive method. Sclerosing treatment of single side-branch varicosities in ten legs demonstrated that merely measuring refilling time (invasively or noninvasively) was not sufficient, because this value did not indicate any improvement in haemodynamics even after successful treatment.

Adult↗
PubMed1971

Amino acid sequence of the light chain from a mouse myeloma protein with anti-hapten activity: evidence for a third type of light chain.

A tentative amino acid sequence has been determined for the light chain of a mouse A-myeloma (MOPC-315) protein with anti-2,4-dinitrophenyl activity. An unusual amino acid sequence in the carboxyl-terminal 104 residues suggests that the chain represents a new class of immunoglobulin light chain. The "variable" segment of this chain (amino-terminal 110 residues) differs at only eight positions from the corresponding segment of the lambda chain of a mouse M-myeloma (MOPC-104) protein with anti-dextran activity.

Alleles↗
PubMed1980

Crossreactivity between the light-emitting systems of distantly related organisms: Novel type of light-emitting compound.

Dinoflagellate luciferin has been found to crossreact and emit light with euphausid photoprotein; and euphausid fluorescent substance gives luminescence with dinoflagellate luciferase. Luciferin and the fluorescent substance, both highly unstable and fluorescent compounds, are biochemically similar but not identical. Preliminary spectral and chemical data suggest that both compounds contain an open-chain polypyrrole structure, novel among compounds so far known to be involved in light emission in any biological system. The dinoflagellates and euphausids are phylogenetically distant; the possibility that the latter obtain the molecule nutritionally from the former is suggested.

Journal Article↗
PubMed2001

Configuration and dynamics of xanthophylls in light-harvesting antennae of higher plants. Spectroscopic analysis of isolated light-harvesting complex of photosystem II and thylakoid membranes.

Resonance Raman excitation spectroscopy combined with ultra low temperature absorption spectral analysis of the major xanthophylls of higher plants in isolated antenna and intact thylakoid membranes was used to identify carotenoid absorption regions and study their molecular configuration. The major electronic transitions of the light-harvesting complex of photosystem II (LHCIIb) xanthophylls have been identified for both the monomeric and trimeric states of the complex. One long wavelength state of lutein with a 0-0 transition at 510 nm was detected in LHCIIb trimers. The short wavelength 0-0 transitions of lutein and neoxanthin were located at 495 and 486 nm, respectively. In monomeric LHCIIb, both luteins absorb around 495 nm, but slight differences in their protein environments give rise to a broadening of this band. The resonance Raman spectra of violaxanthin and zeaxanthin in intact thylakoid membranes was determined. The broad 0-0 absorption transition for zeaxanthin was found to be located in the 503-511 nm region. Violaxanthin exhibited heterogeneity, having two populations with one absorbing at 497 nm (0-0), 460 nm (0-1), and 429 nm (0-2), and the other major pool absorbing at 488 nm (0-0), 452 nm (0-1), and 423 nm (0-2). The origin of this heterogeneity is discussed. The configuration of zeaxanthin and violaxanthin in thylakoid membranes was different from that of free pigments, and both xanthophylls (notably, zeaxanthin) were found to be well coordinated within the antenna proteins in vivo, arguing against the possibility of their free diffusion in the membrane and supporting our recent biochemical evidence of their association with intact oligomeric light-harvesting complexes (Ruban, A. V., Lee, P. J., Wentworth, M., Young, A. J., and Horton, P. (1999) J. Biol. Chem. 274, 10458-10465).

Carotenoids↗