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PubMed2005

Highly repeatable all-solid-state polarization-state generator.

We report an all solid-state polarization-state generator that uses magneto-optic polarization rotators. The device can generate either five or six distinctive polarization states uniformly across a Poincaré sphere with repeatability better than 0.1 degrees. It is ideal for polarization analysis, swept-wavelength measurement, and monitoring of polarization-related parameters and signal-to-noise ratios of optical networks.

Journal Article↗
PubMed1976

NMR-studies of triiodothyropropionic acid in ethanol-HCl.

The barrier to rotation in the N-acetyl methyl ester of the thyroxine was found to be 8.6 kcal mol-1. Previous experiments determining the barrier to rotation in triiodothyropropionic acid in HCl-ethanol were shown to be in error.

Ethanol↗
PubMed2005

Do rotation coordinates provide the substrate for a mental protractor?

In previous studies, we have found that the accuracy in judging collinearity of lines or dots varies considerably from one subject to another as a function of the relative angle of the stimulus elements. A model of errors generally shows large excursions across several subranges of angular position. These do not appear to be motor errors, at least not ones that are well separated from perceptual mechanisms. The errors are most likely generated at primary visual cortex, or beyond. We examined and modeled accuracy in judging collinearity of dot pairs, varying the angular position of the dots through 360 degrees, the distance between the dots (stimulus span), and the distance at which the subject was required to respond (response span). Subjects manifested idiosyncratic profiles of error across angular positions, as reported previously. But across the tested range of spans, from 4 to 8 deg, the errors tended to be the same, irrespective of stimulus or response span. This suggests that the judgments are based on a radial (angular) measure of spatial position. We discuss these results in the context of proposals that the brain maps spatial position using rotation coordinates. These new data are consistent with the hypothesis that subjects use the z-axis coordinates as a mental protractor for judging angular position and collinearity.

Humans↗
PubMed1975

Fluorescence polarization studies on the conformational transition of bovine plasma albumin in acidic solutions.

The acid-induced isomerization (the N-F transition) and expansion of bovine plasma albumin were studied by measuring fluorescence polarization and lifetime of the excited state of tryptophyl fluorophors. Most of the changes (decreases) in the reciprocal of fluorescence polarization and lifetime of the excited state correlated exactly with the N-F1 transition and/or the initial part of the N-F transition. These findings suggest that though the N-F transition is the cooperative pH-dependent conformational transition, the N-F transition clearly involves an intermediate step, such as the N-F1 and F1-F2 transitions. Rotational relaxation times for the N- and F-forms obtained by Perrin plot of tryptophyl fluorescence polarization were approximately 75 and 120-180 ns, respectively. The unexpected short rotational relaxation time of 75 ns of the N-form might be due to the rotational freedom of the tryptophyl side chain itself and/or of small flexible loci where tryptophyl fluorophors attach.

Animals↗
PubMed1978

Quantitation of hindered rotations of diphenylhexatriene in lipid bilayers by differential polarized phase fluorometry.

Diffusional motions of 1,6-diphenyl-1, 3, 5-hexatriene (DPH) were observed by differential polarized phase fluorometry. The measurements indicated that the depolarizing rotations of DPH in propylene glycol are isotropic. The results in vesicles of dimyristoyl-l-alpha-phosphatidylcholine indicated that diffusional rotations of DPH are dominated by hindered torsional motions. Combined use of both differential phase and steady-state anisotropy measurements showed that the average rotational angle of DPH, at times long compared to the fluorescence lifetime, is limited to about 23 degrees at temperatures below the transition temperature of the lipid and that these rotations become less hindered above the transition temperature. The evidence that the depolarizing rotations of DPH in a lipid bilayer are different from those in an isotropic solvent calls into question the meaning of membrane microviscosity as determined by fluorescence anisotropy.

Fluorescent Dyes↗
PubMed2002

Determination of the absolute configuration of (+)-2,7(14),10-bisabolatrien-1-ol-4-one from Japanese cedar, Cryptomeria japonica.

The absolute configuration of (+)-2,7(14),10-bisabolatrien-1-ol-4-one, a peculiar sesquiterpenol in the Japanese cedar, Cryptomeria japonica, was determined as (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one by comparing the specific rotation values of cryptomeriones respectively converted from (+)-2,7(14),10-bisabolatrien-1-ol-4-one and synthesized from (R)-(-)-carvone.

Cryptomeria↗
PubMed1989

Fluorescence depolarization of cis- and trans-parinaric acids in artificial and red cell membranes resolved by a double hindered rotational model.

Although steady-state anisotropy measurements of phase-sensitive probes provide a qualitative description of the phase behavior of biomembranes, there is little information about the physical state of lipid domains. We have developed a ground-state double hindered rotator model (DHR) for fluorescence anisotropy decay, in which probes possess separate rotational correlation times and r infinity in each phase. To validate the model, multifrequency differential phase angles (delta) and modulation amplitudes (lambda) were measured in a two-compartment cuvette with combinations of POPOP, TMA-DPH, and DPH in isotropic solvents and in DPPC liposomes. Rotational parameters obtained by fitting the DHR model were similar to those of a single hindered rotator model fitted to data obtained separately for each probe. As predicted by the model, negative delta and decreasing lambda with increasing modulation frequency were obtained when fluorophores in isotropic solvents were paired with fluorophores in DPPC liposomes. The rotational parameters of the phase-sensitive fluorophores cis-parinaric (cPnA) and trans-parinaric (tPnA) acid in DPPC/DMPC (1:0, 0:1, and 1:1) liposomes were determined at 15-40 degrees C. Two lifetimes (1 and 3 ns) were obtained above the phase transition temperature (Tc); greater than 95% of the fluorescence intensity was described by two lifetimes (3-9 and 12-32 ns) below Tc. Negative delta values were obtained when solid-phase lipid was present. r infinity varied from 0.26-0.32 below to 0.11-0.14 above Tc; at intermediate T, where two phases coexists, r infinity values were approximately 0.23 and approximately 0.31. These data indicate very hindered PnA rotation in solid-phase lipid.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1982

Rotational motion of cytochrome c derivatives bound to membranes measured by fluorescence and phosphorescence anisotropy.

Molecular motion of metal-free and metal-substituted cytochrome c derivatives was examined using the anisotropy of emissions from the singlet and the triplet states. The anisotropy of fluorescence provides a means to study the motion of cytochrome c in the nanosecond time scale, since the fluorescence lifetime of metal-free cytochrome c is around 10 ns. We find that the anisotropy of fluorescence of metal-free cytochrome c when bound to mitochondria does not decay, but when bound to phospholipids has a small component which decays independently of the rotation of the whole molecule. The use of phosphorescence extends the time scale for study into the millisecond regime, since the lifetime of the excited triplet state of zinc cytochrome c, as measured by triplet-triplet absorption and phosphorescence emission is approximately equal to 9 ms for free zinc cytochrome c and 7 ms for mitochondrial membrane-bound zinc cytochrome c at room temperature. The decay of anisotropy of phosphorescence emission of mitochondrial membrane-bound zinc cytochrome c is clearly biphasic; the fast component corresponds to a rotational relaxation time of 300 mus and the slow component with relaxation time of approximately equal to 6 ms. The slow component appears to be due to the rotation of the entire mitochondrion, whereas the fast component was interpreted to be due to the rotation of cytochrome c in a cone about a single axis perpendicular to the plane of the membrane surface.

Animals↗
PubMed1981

Purification of a trypsin-insensitive fragment of spectrin from human erythrocyte membranes.

When spectrin is treated with trypsin, a series of polypeptide fragments is generated, One particular fragment having an approximate molecular weight of 80 000 constitutes 18% of the trypsin-digested mixture and is trypsin-insensitive. This fragment has been isolated and purified by gel filtration followed by ion-exchange chromatography. The molecular weight of the fragment, as seen from sedimentation equilibrium measurements and from gel electrophoresis, both in the presence and absence of detergent, is close to 80 000. There was no evidence of self-association under the conditions used. Changes in the specific rotation at 365 nm were used to detect temperature-dependent conformation changes in the fragment and to compare these changes with those in the intact spectrin molecule. The fragment undergoes temperature-dependent transitions centered at 46 and 58 degrees C, similar to those in intact spectrin (49 and 55 degrees C). Although the thermal transitions exhibited by intact spectrin are markedly salt-dependent, those shown by the fragment are not. ORD (optical rotary dispersion) measurements indicate 53% apparent alpha-helix in the fragment, compared to 68% in intact spectrin. Antibodies raised against the fragment cross-react only with band 1, the largest polypeptide of spectrin, indicating that the fragment is derived from band 1.

Electrophoresis, Polyacrylamide Gel↗
PubMed2006

Effect of polarization state on electro-optic coupling and its application to polarization rotation.

The effect of the polarization state on electro-optic coupling is studied by using the wave coupling theory of the linear electro-optic effect. The numerical results show that the polarization state obviously influences the electro-optic coupling. The conditions for realizing perfect coupling are emphasized. As an application of perfect coupling, a novel polarization rotator, which can rotate the polarization of a light beam with an arbitrary angle but keep the output intensity unchanged, is presented.

Journal Article↗
PubMed1976

Changes in E. coli cell envelope structure caused by uncouplers of active transport and colicin E1.

It is of interest to inquire whether agents that uncouple or deenergize membranes cause concomitant structural changes. The agents considered here are the uncoupler carbonyl cyanide-p-trifluoromethoxyphenylhydrazone and the bacteriocidal protein colicin E1, agents for which there is some precedent for believing that they interact with membranes. In intact E. coli ML 308-225 cells the inhibition of [14C]-PROLINE ACtive transport by FCCP increases with uncoupler concentration from approximately 20% at 2 muM to approximately 100% at 5 muM. The increase in the rotational relaxation time (rho) of the cell-bound fluorescent probe N-phenyl-1-naphthylamine (PhNap)1 and 8-anilino-1-naphthalene-sulfonate (ANS) under these conditions shows the same dependence on FCCP concentration. For cells treated with EDTA to remove part of the outer lipopolysaccharide layer, inhibition of proline transport and the increase in rho value of ANS show the same dependence on FCCP concentration with saturation at 0.3 muM. EDTA treatment causes a large increase in the binding and rotational relaxation time of PhNap, the latter quantity approaching a value obtained with purified inner membrane. Similar effects are produced in untreated cells by 5muM FCCP...

Biological Transport, Active↗
PubMed1992

High-speed rotational angioplasty-induced echo contrast in vivo and in vitro optical analysis.

High-speed rotational angioplasty is being evaluated as an alternative interventional device for the endovascular treatment of chronic coronary occlusions. It has been postulated that this type of angioplasty device may produce particulate debris or cavitations that induce myocardial ischemia. To determine the clinical presence of myocardial ischemia during rotational angioplasty, echocardiographic monitoring for wall motion abnormalities was performed in 9 patients undergoing rotational atheroablation using the Auth Rotablator for 10-sec intervals at 150,000 and 170,000 rpm. No wall motion abnormalities were detected in 5 patients evaluated with transesophageal echocardiography or in 4 patients monitored transthoracically, although AV block developed in one patient. Video intensitometry of the myocardial contrast effect for rotation times ranging from 3 to 20 sec found transient contrast enhancement of the myocardium supplied by the treated vessel. Intensity varied over time with half-time decay between 5.6 and 40 sec, indicating the likelihood of microcavitation. An in vitro model was constructed to measure the cavitation potential of the Auth Rotablator. A burr of 1.25 mm diameter rotating at 160,000 rpm achieves a velocity in excess of the 14.7 m/sec critical cavitation velocity. Testing the device in fresh human blood and distilled water produced microcavitations responsible for the enhanced echo effect, with the intensity and longevity of cavitation more pronounced in blood and proportional to the rotation time and speed. The mean size of the microcavitation bubbles in water was 90 +/- 33 (52-145) microns measured from photographs taken with a copper vapour laser emitting light pulses of 50 nsec duration as light source. The mean velocity of bubbles was found to be 0.62 +/- 0.30 ranging from 0.23 to 1.04 m/sec. It was measured via the motion of the bubbles during 5 laser pulses within 800 nsec. Clearly, microcavitations are associated with enhanced myocardial echo contrast effect.

Angioplasty, Balloon, Coronary↗
PubMed2002

Compartments in arteriovenous malformation nidi demonstrated with rotational three-dimensional digital subtraction angiography by using selective microcatheterization. Report of three cases.

Although in several histological studies of arteriovenous malformation (AVM) nidi the presence of compartments has been documented, no clinical study has been published. The present study was conducted to determine the presence of nidus compartments in clinical cases by using a new radiographic method. Two patients with unruptured and one with a ruptured AVM (all Spetzler-Martin Grade III) were studied. A microcatheter was superselectively introduced into each of two or three feeding arteries of the AVMs under three-dimensional (3D) angiographic guidance to obtain 3D images of the nidus by using rotational digital subtraction angiography. On 3D images the different feeding arteries were found to be independent from one another, which allowed the authors to confirm the presence of compartments. On the other hand, separate feeding arteries often had a common draining vessel. Compartments in AVM nidi were demonstrated by a novel rotational 3D angiographic procedure by using superselective microcatheterization, which should be useful for designing treatment strategies for large and complex AVMs.

Angiography, Digital Subtraction↗
PubMed1997

Correlated bond rotations in interactions of arginine residues with ligand carboxylate groups in protein ligand complexes.

The 1H/15N HSQC NMR spectra of complexes of Lactobacillus casei dihydrofolate reductase containing methotrexate recorded at 1 degree C show four resolved signals for the four NH(eta) protons of the Arg57 residue. This is consistent with hindered rotation in the guanidino group resulting from interactions with the alpha-carboxylate of methotrexate. Increasing the temperature causes exchange line-broadening and coalescence of signals. Rotation rates for the N(epsilon)C(zeta) and C(zeta)N(eta) bonds have been calculated from lineshape analysis and from zz-HSQC exchange experiments. The interactions between the methotrexate alpha-carboxylate group and the Arg57 guanidino group decrease the rotation rates for the N(epsilon)C(zeta) bond by about a factor of 10 and those for the C(zeta)N(eta) bonds by more than a factor of 100 with respect to their values in free arginine. Furthermore, the relative rates of rotation about these two bonds are reversed in the protein complexes compared with their values in free arginine indicating that there are concerted rotations about the N(epsilon)C(zeta) bond of the Arg57 guanidino group and the C'C(alpha) bond of the glutamate alpha-carboxylate group of methotrexate.

Arginine↗
PubMed1996

Rotational Spectrum of the Excited Vibrational States of DCOOH and Assignment of Optically Pumped Laser Transitions

The rotational spectrum of DCOOH in the 175-335 GHz region was investigated. Analysis of the spectrum made it possible to assign several dozen transitions in the nu6, nu8, and nu5 vibrational states and to determine the rotational and centrifugal distortion constants. The derived parameters of the nu6 state allowed four optically pumped laser transitions to be assigned. In addition, the ground state parameters for DCOOH and D13COOH have been improved and for the first time those for DC18OOH and DCO18OH have been obtained.

Journal Article↗
PubMed1993

An efficient route to N-palmitoyl-D-erythro-sphingomyelin and its 13C-labeled derivatives.

We describe here a practical and efficient route to a homogeneous N-palmitoyl-D-erythro-sphingomyelin and its 13C-labeled derivatives. (2S,3R,4E)-2-Azido-3-(tert-butyldimethylsilyloxy)-4-octad ecene-1-ol 1 was converted to the sphingosine equivalent 2 by treatment with triphenylphosphine and water. Amine 2 was then coupled with palmitic acid, affording the ceramide derivative 3a. In the following two reactions the phosphorylcholine functional group was generated by using 2-chloro-2-oxo-1,3,2-dioxaphospholane and trimethylamine, respectively. The final deprotection of the secondary hydroxyl group in 5a produced the desired N-palmitoyl-D-erythro-sphingomyelin 6a. The overall yield of this five-step synthesis is 43%. The melting point, 213-215 degrees C, the specific rotation, [alpha]20D = +6.8 (c = 1.3, CH2Cl2/MeOH 1:1) and 1H- and 13C-NMR data indicate that the synthetic sphingomyelin is enantiomerically pure. The 13C-labeled derivatives 6b, 6c and 6d were synthesized by employing the same scheme.

Carbon Isotopes↗