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PubMed2000

Azuki bean cells are hypersensitive to cadmium and do not synthesize phytochelatins.

Suspension-cultured cells of azuki bean (Vigna angularis) as well as the original root tissues were hypersensitive to Cd (<10 microM). Repeated subculturings with a sublethal level of Cd (1-10 microM) did not affect the subsequent response of cells to inhibitory levels of Cd (10-100 microM). The azuki bean cells challenged to Cd did not contain phytochelatin (PC) peptides, unlike tomato (Lycopersicon esculentum) cells that have a substantial tolerance to Cd (>100 microM). Both of the cell suspensions contained a similar level of reduced glutathione (GSH) when grown in the absence of Cd. Externally applied GSH to azuki bean cells recovered neither Cd tolerance nor PC synthesis of the cells. Furthermore, enzyme assays in vitro revealed that the protein extracts of azuki bean cells had no activity converting GSH to PCs, unlike tomato. These results suggest that azuki bean cells are lacking in the PC synthase activity per se, hence being Cd hypersensitive. We concluded that the PC synthase has an important role in Cd tolerance of suspension-cultured cells.

Aminoacyltransferases↗
PubMed2005

Modulated one-dimensional structure of [Cd(NH3)3Ni(CN)4].

The crystal structure of [Cd(NH(3))(3)Ni(CN)(4)] has been solved and refined as an incommensurate structure in four-dimensional superspace. The Xcalibur point-detector diffractometer was used for data collection up to the third-order satellites. The structure was refined from 3496 observed reflections to a final R value of 0.0371. The modulation strongly affects all the atoms of the structure. The dominating feature of the modulation is the incommensurate alternation between octahedrally and tetrahedrally coordinated Cd atoms in the electroneutral chains [-Cd(NH(3))(n)-NC-Ni(CN)(2)-CN-](infinity) (n alternates between 2 and 4). The chain is propagated along the a axis, in which the [Cd(NH(3))(n)](2+) cations are linked by square [Ni(CN)(4)](2-) anions. The atomic positional modulations, having mainly a transversal character in the c-direction, exhibit a switching character that can be described by the crenel and sawtooth functions. The effectively pentagonal coordinated cadmium positions were detected in the intermediate regions.

Ammonia↗
PubMed2002

Nucleation rate determination by a concentration pulse technique: application on ferritin crystals to show the effect of surface treatment of a substrate.

The nucleation of horse spleen ferritin (HSF) crystals on substrates was investigated using a new modification of the double pulse technique. The influence of three different structureless substrates (glass, glass covered by methyl groups and poly-L-lysin template) on the nucleation was studied. The boundaries in the phase-diagram, which separate zones of crystal nucleation and growth were obtained by keeping pH = 5.0, and using CdSO(4) as crystallizing agent. The steady-state nucleation rates were determined. The energy required for critical nuclei formation was evaluated (10(-13) erg) and the sizes of critical nuclei were found (5 and 2 molecules).

Animals↗
PubMed2004

Beamline 10.3.2 at ALS: a hard X-ray microprobe for environmental and materials sciences.

Beamline 10.3.2 at the ALS is a bend-magnet line designed mostly for work on environmental problems involving heavy-metal speciation and location. It offers a unique combination of X-ray fluorescence mapping, X-ray microspectroscopy and micro-X-ray diffraction. The optics allow the user to trade spot size for flux in a size range of 5-17 microm in an energy range of 3-17 keV. The focusing uses a Kirkpatrick-Baez mirror pair to image a variable-size virtual source onto the sample. Thus, the user can reduce the effective size of the source, thereby reducing the spot size on the sample, at the cost of flux. This decoupling from the actual source also allows for some independence from source motion. The X-ray fluorescence mapping is performed with a continuously scanning stage which avoids the time overhead incurred by step-and-repeat mapping schemes. The special features of this beamline are described, and some scientific results shown.

Arabidopsis↗
PubMed2005

Crystallization of the C-terminal globular domain of avian reovirus fibre.

Avian reovirus fibre, a homotrimer of the sigmaC protein, is responsible for primary host-cell attachment. Using the protease trypsin, a C-terminal sigmaC fragment containing amino acids 156-326 has been generated which was subsequently purified and crystallized. Two different crystal forms were obtained, one grown in the absence of divalent cations and belonging to space group P6(3)22 (unit-cell parameters a = 75.6, c = 243.1 A) and one grown in the presence of either zinc or cadmium sulfate and belonging to space group P321 (unit-cell parameters a = 74.7, c = 74.5 A and a = 73.1, c = 69.9 A for the Zn(II)- and Cd(II)-grown crystals, respectively). The first crystal form diffracted synchrotron radiation to 3.0 A resolution and the second form to 2.2-2.3 A. Its closest related structure, the C-terminal fragment of mammalian reovirus fibre, has only 18% sequence identity and molecular-replacement attempts were unsuccessful. Therefore, a search is under way for suitable heavy-atom derivatives and attempts are being made to grow protein crystals containing selenomethionine instead of methionine.

Cadmium Compounds↗
PubMed2005

Evaluation of fully 3-D emission mammotomography with a compact cadmium zinc telluride detector.

A compact, dedicated cadmium zinc telluride (CZT) gamma camera coupled with a fully three-dimensional (3-D) acquisition system may serve as a secondary diagnostic tool for volumetric molecular imaging of breast cancers, particularly in cases when mammographic findings are inconclusive. The developed emission mammotomography system comprises a medium field-of-view, quantized CZT detector and 3-D positioning gantry. The intrinsic energy resolution, sensitivity and spatial resolution of the detector are evaluated with Tc-99m (140 keV) filled flood sources, capillary line sources, and a 3-D frequency-resolution phantom. To mimic realistic human pendant, uncompressed breast imaging, two different phantom shapes of an average sized breast, and three different lesion diameters are imaged to evaluate the system for 3-D mammotomography. Acquisition orbits not possible with conventional emission, or transmission, systems are designed to optimize the viewable breast volume while improving sampling of the breast and anterior chest wall. Complications in camera positioning about the patient necessitate a compromise in these two orbit design criteria. Image quality is evaluated with signal-to-noise ratios and contrasts of the lesions, both with and without additional torso phantom background. Reconstructed results indicate that 3-D mammotomography, incorporating a compact CZT detector, is a promising, dedicated breast imaging technique for visualization of tumors < 1 cm in diameter. Additionally, there are no outstanding trajectories that consistently yield optimized quantitative lesion imaging parameters. Qualitatively, imaging breasts with realistic torso backgrounds (out-of-field activity) substantially alters image characteristics and breast morphology unless orbits which improve sampling are utilized. In practice, the sampling requirement may be less strict than initially anticipated.

Breast Neoplasms↗
PubMed2006

Bleustein-Gulyaev-Shimizu surface acoustic waves in two-dimensional piezoelectric phononic crystals.

In this paper, we present a study on the existence of Bleustein-Gulyaev-Shimizu piezoelectric surface acoustic waves in a two-dimensional piezoelectric phononic crystal (zinc oxide, ZnO, and cadmium-sulfide, CdS) using the plane wave expansion method. In the configuration of ZnO (100)/CdS(100) phononic crystal, the calculated results show that this type of surface waves has higher acoustic wave velocities, high electromechanical coupling coefficients, and larger band gap width than those of the Rayleigh surface waves and pseudosurface waves. In addition, we find that the folded modes of the Bleustein-Gulyaev-Shimizu surface waves have higher coupling coefficients.

Acoustics↗
PubMed1986

Local variation in cutaneous and subcutaneous blood flow measured by CdTe(C1) minidetectors in normal and psoriatic skin.

The accuracy of the 133Xe washout method and the validity of newly developed cadmium telluride CdTe(Cl) minisemiconductor detectors were estimated by performing comparative, simultaneous measurements of both cutaneous (CBF) and subcutaneous (SBF) blood flow using 2 conventional scintillation sodium iodide NaI(Tl) and CdTe(Cl) detectors over the same radioactive depot in each of 10 individuals. The accuracy of the 133Xe washout method was found to be 13-15% (C.V.) for the CBF measurements and 9-12% (C.V.) for the SBF measurements. The CdTe(Cl) detectors, which have a weight of 20 g and were attached directly over the radioactive depot, may replace stationary NaI(Tl) detectors placed 20 cm from the depot for measurements of both CBF and SBF. Two CdTe(Cl) detectors were used for estimations of the local variation in CBF and SBF within a distance of 5 cm in normal skin of 10 individuals. The C.V. was 7% for the CBF measurements and 18% for the SBF measurements. Measurements of CBF and SBF were performed in 6 psoriatic patients who, after about 1 week of antipsoriatic treatment with beech tar, developed typical Woronoff rings. The local CBF differed significantly from the center of psoriatic plaques to the margin, in the Woronoff ring, and in nonlesional skin. In contrast, SBF was remarkably equal within the plaque and in the Woronoff ring. The color of the Woronoff ring cannot be ascribed to a local cutaneous vasoconstriction. Cutaneous blood flow in chronic stable, lesional psoriatic skin was significantly lower than previously published values for active lesional psoriatic skin, but significantly higher than CBF in normal individuals. Measurements of CBF in tetrahydrofurfuryl nicotinic acid (Trafuril)-treated skin showed higher values than measurements of CBF in the postischemic hyperemia period both in normal and in lesional psoriatic skin. Trafuril induced a significant increase of CBF in both lesional and nonlesional skin. The high CBF rates in lesional psoriatic skin are not due to a maximally, passively dilated vascular bed.

Adult↗
PubMed1991

Heat shock proteins in cultured human keratinocytes and fibroblasts.

Heat shock induces in cells the synthesis of specific proteins called heat-shock proteins. We have compared the induction of these proteins in human keratinocytes, skin fibroblasts, and a human epithelial tumor cell line following exposure to weak and strong inducing agents (heat, cadmium sulphate, and sodium arsenite). The induction of heat shock proteins was measured in cells by one-dimensional gel electrophoresis of [35S] methionine-labeled proteins and by immunofluorescence using a specific HSP72 monoclonal antibody. Both HSP90 and HSP116 were constitutively expressed in these cell types. Exposure of these cells to weak inducing agents such as heat or cadmium sulphate resulted in the synthesis of HSP72 and HSP90, whereas HSP28 and HSP116 synthesis was detected in keratinocytes and fibroblasts following exposure to the strong inducing agent sodium arsenite. In addition, sodium arsenite induced the synthesis of HSP46 in human keratinocytes. Immunofluorescence demonstrated a rapid and reversible accumulation of the 72-kD heat shock protein within the nucleolus of heat-stressed human keratinocytes and fibroblasts.

Arsenic↗
PubMed2004

Anatomical and functional evidence for a role of arginine-vasopressin (AVP) in rat olfactory epithelium cells.

The olfactory epithelium (OE) is composed of olfactory sensory neurons (OSNs) and sustentacular cells; it lies in the nasal cavity where it is protected by a thin mucus layer. The finely regulated composition of this mucus provides OSN with a suitable ionic environment. To maintain the functional integrity of the epithelium despite permanent physical, chemical and microbial aggressions, both OSNs and surrounding sustentacular cells are continuously renewed from globose basal cells. Moreover, the sense of smell is involved in so numerous behaviours (feeding, reproduction, etc.) that it has to cross-talk with the endocrine and neuroendocrine systems. Thus, besides its sensory function, the olfactory epithelium is thought to undergo a lot of complex regulatory processes. We therefore studied the effects of various neuropeptides on primary cultures of Sprague-Dawley rat olfactory epithelium cells. We found that arginine-vasopressin (AVP) triggered a robust, dose-dependent calcium increase in these cells. The cell response was essentially ascribed to the V1a AVP receptor, whose presence was confirmed by RT-PCR and immunolabelling. In the culture, V1a but not V1b receptors were present, mainly localized in neurons. In the epithelium, both subtypes were found differentially distributed. V1a-R were localized mainly in globose basal cells and at the apical side of the epithelium, in the area of the dendritic knobs of OSNs. V1b-R were strongly associated with Bowman's gland cells and globose basal cells. These localizations suggested potential multifaceted roles of a hormone, AVP, in the olfactory epithelium.

Animals↗
PubMed1998

Calcium current activated by potassium ions in voltage-clamped rat hippocampal pyramidal neurones.

1. Neuronal activity results in local elevation of extracellular K+ concentration ([K+]o). 2. Using the patch-clamp technique in the whole-cell configuration, we investigated whether extracellular K+ activates non-voltage-operated Ca2+ channels in pyramidal cells cultured from rat embryonic hippocampi. 3. K+ (12 mM) reversibly activated a sustained inward current at a holding potential of -100 mV. Membrane conductance and variance of noise were significantly increased by K+. This current could be observed at membrane potentials negative to +60 mV. 4. Inhibitors of inward rectifier K+ channels and hyperpolarization-induced cation current reduced the current only at potentials negative to -50 mV. 5. The K+-induced current was activated in Na+-free but not in Ca2+-free medium, did not depend on cytosolic [Cl-], and was blocked by Cd2+ but not by organic channel inhibitors. 6. Half-maximal activation of the current (at -100 mV) was attained at [K+]o approximately 20 mM. 7. The current is similar to Igl, a K+-induced Ca2+ current described in glomerulosa cells. It was also present in pyramidal cells from prefrontal cortex but not in hippocampal bipolar and glial cells. 8. Activation of K+-induced Ca2+ current may elevate cytoplasmic [Ca2+] at [K+]o levels which are insufficent to activate voltage-dependent Ca2+ channels.

2-Amino-5-phosphonovalerate↗
PubMed1983

Comparison of portable CdTe(Cl) detectors with stationary NaI(Tl) detectors for subcutaneous 133Xe disappearance measurements.

133Xe washout measurements from locally injected depots in the subcutaneous tissue of the thigh have been performed intermittently by a NaI(Tl) detector placed 15 cm from the depot and a cadmium telluride [CdTe(Cl)] detector fixed to the skin surface above the depot. In 19 experiments, the measurements were performed during rest, before and after bicycling and during circulatory arrest during an occlusion cuff pressure of 240-250 mmHg. The disappearance rates measured by the two detector systems showed a linear correlation (r = 0.934, P less than 0.001). However, the rate constants measured by the CdTe(Cl) detector were an average of 1.48 times the values obtained by the NaI(Tl) detector during a period of 1-4 h after the injection. The coefficient of variation of the proportionality factor is 3.3%. Only the central part of the local depot area is exposed to the CdTe(Cl) detector. Using the NaI(Tl) detector and lead shielding of the peripheral or central part of the depot area, it was demonstrated that the disappearance rates obtained reflect the measuring geometries. The correction itself is therefore due to differences in the measuring geometries of the two detector types, and possibly to diffusion and convection of xenon. For quantitative determination of the subcutaneous blood flow, the disappearance rate constants determined by the CdTe(Cl) detector thus have to be corrected by division with the factor 1.48.

Adolescent↗
PubMed1984

Subcutaneous measurements of 133Xe disappearance with portable CdTe(Cl) detectors: elimination of interference from combined convection and diffusion.

Portable, solid state, cadmium telluride [CdTe(C1)] detectors were used for measurements of 133Xe-disappearance rate constants as a measure of subcutaneous (s.c.) blood flow. To eliminate the disturbance on the measurements from combined local convection and diffusion of xenon in the s.c. tissue, two methods were demonstrated to be feasible in both control persons and anaesthetized rabbits. A small volume (50-80 microliters) was injected into the s.c. tissue at a depth of 5 mm and the CdTe(C1) detector elevated 20 mm above the skin surface. In this situation identical disappearance rate constants were recorded by the CdTe(C1) detector and the NaI(T1) reference detector at 15-20 cm from the depot. Similiar results were obtained when either a large volume (greater than or equal to 800 microliters of Xe in humans) was injected into the s.c. tissue or the labelling was performed with a smaller volume in an atraumatic uniform manner to obtain a constant Xe concentration exceeding the field of view of the CdTe(C1) detector, which in these cases was attached directly to the skin surface. The coefficients of variation (CV) of the disappearance rate constants measured by the CdTe(C1) detector were 9% and 11%, and these values did not differ significantly from each other (P greater than 0.2), or from CV-values calculated from measurements with NaI(T1) detectors.

Adolescent↗
PubMed1995

Involvement of protein kinase C in the delayed cytoprotection following sublethal ischaemia in rabbit myocardium.

Rabbit hearts were preconditioned with four 5 min coronary artery occlusions 24 h before 30 min coronary occlusion with 120 min reperfusion. Preconditioning significantly reduced the percentage of myocardium infarcting within the risk zone from 49.1 +/- 4.3% to 31.8 +/- 3.5% (P < 0.05). When the protein kinase C (PKC) inhibitor, chelerythrine, was administered just before preconditioning, the delayed protection against infarction 24 h later was abolished. We conclude that the delayed cytoprotective response associated with ischaemic preconditioning of myocardium is likely to involve the early activation of one or more PKC subtypes.

Alkaloids↗
PubMed1996

Interactions of sulfates of divalent metals in nickel-sulfate-sensitive patients.

70 nickel-sensitive subjects who previously gave positive patch test response to 10 microliters of nickel sulfate 0.1 M, were patch tested to 10 microliters of mixed aqueous solutions containing nickel sulfate 0.1 M+magnesium sulfate 0.3 M, nickel sulfate 0.1 M+zinc sulfate, 0.3 and 0.5 M, respectively, nickel sulfate 0.1 M+ manganese sulphate 0.3 and 0.5 M, respectively nickel sulphate 0.1 M+ cadmium sulfate 0.1 and 0.3 M, respectively, nickel sulfate 0.1 M+iron sulfate (III) 0.1 and 0.3 M, respectively, and to 10 microliters of aq. cadmium sulfate 0.1 M, aq. cadmium sulfate 0.3 M, aq. iron sulfate 0.1 M, aq. iron sulfate 0.3 M. The results showed that, whilst sulfates of divalent metals with similar size and redox properties (Mg, Zn and Mn) were able to reduce or to suppress, in a dose-dependent way, the majority (75%) of nickel reactions, those with large radius and different oxidation state(Fe III), generally gave an increase in the reactions. In about 15% of the tested subjects, an increase in all the positive reactions to the mixed solutions was found. The findings seem to demonstrate that in only a majority but not all of nickel sulfate allergic reactions, is Ni(II) able to substitute for divalent ions with similar properties at the ion sites of some proteins. This tendency reproduces the results of experimental systems, in which nickel toxicity and cancerogenity are considered responsible. In contrast, in about 15% of the tested subjects, there was a general enhancement of the reactions. In these cases, either the occurrence of a "hyper-irritable" skin caused by the adopted test system or, more likely, the formation of Ni complexes with different geometries, is hypothesized.

Adult↗
PubMed1993

Growth suppression of normal mammary epithelial cells by wild-type p53.

We examined the status of the p53 gene in the HC11 normal mammary epithelial cells. Two mutations were identified: a Cys to Trp change at codon 138 and a microdeletion of codon 123 to 130 resulting from mutation of the splice acceptor site. These two mutations were independent, and no wild-type p53 allele was found. Introduction of wt-p53 strongly inhibited growth in monolayer. Thus, the absence of wt-p53 can be sufficient for the immortalization of mammary cells.

Amino Acid Sequence↗
PubMed1990

A study of the developmental changes in outward currents of rat ventricular myocytes.

1. In ventricular muscle of rat heart, the action potential undergoes a major developmental change in shape in the days and weeks immediately after birth. Potassium (K+) currents which may affect the shape of the action potential have been studied using a whole-cell voltage-clamp technique with single cells from the ventricles of rats aged 1-10 days. All recordings were made at 22-23 degrees C. 2. Three discrete ages were chosen. 1-day (cells isolated within 24 h of birth), 5-day and 10-day rats. These parallel the developmental action potential shortening from neonatal towards adult type. Action potentials of single myocytes were initially of long duration at 1 day with a prominent plateau phase, but had shortened somewhat by 10 days of age. The 5-day group exhibited an action potential transitional in character between the earlier and later groups of cells. 3. Potassium current blocking agents were used to assess the importance of the various outward K+ currents for the action potential waveform at different ages. 4-Aminopyridine (4-AP; 2 x 10(-3) M) which preferentially blocks voltage-activated transient outward currents affected action potentials at all ages, but increases in duration were most pronounced in the 10-day group. Only a small prolongation of the initial phase of repolarization of 1-day action potentials was seen. Extracellular barium chloride, 0.1-2 x 10(-3) M, a blocker of inwardly rectifying potassium channels, had a marked slowing effect on repolarization in all the three age groups. Resting membrane depolarization was also produced by barium. 4. Developmental changes in the inwardly rectifying background current (IK1) and the cardiac transient outward current, It, were investigated. IK1 was recorded as the current sensitive to 2 x 10(-3) M-BaCl2 during voltage-clamp steps from a holding potential of -90 mV. It was found to decrease in magnitude, approximately by a factor of three, from 15 to 5 pA/pF during the first ten postnatal days. This reduction can explain the maturational slowing of repolarization during the final phase of the action potential in rat heart. 5. Current-voltage relations for IK1 from the three age groups crossed at the zero current potential at approximately -90 mV, near the calculated VK for the pipette filling solution and an external bath K+ concentration of 5 x 10(-3) M. This suggests that IK1 channels in these cells are quite selective for K+ ions and that developmental changes in the potassium selectivity are not responsible for changes in IK1.(ABSTRACT TRUNCATED AT 400 WORDS)

4-Aminopyridine↗