Determination and characterisation of the surface charge properties of the bacteriophage M13 to assist bio-nanoengineering

Hauswirth et al. (1968) proposed that epinephrine acts on iKK2 by adding its own positive charge to the external membrane surface near the iKK2 channel. This hypothesis was tested by using noncationic compounds, theophylline and R07-2956, which mimicked epinephrine's effects on pacemaker activity and on iKK2. In maximally effective doses, theophylline or R07-2956 occluded the effect of epinephrine, indicating a shared final common mechanism. Since theophylline and R07-2956 are noncationic at pH 7.4, the common mechanism cannot be a direct change in external surface charge. On the contrary, epinephrine does not interfere with the voltage shift produced by La+++, which is thought to modify the external surface charge. The results argue against the original hypothesis but leave open the possibility that an alteration in internal surface charge generates the observed voltage shift. The potency of theophylline and R07-2956 as phosphodiesterase inhibitors suggests that the final common mechanism begins with the elevation of intracellular cyclic AMP, leading to a saturable process which limits the voltage shift's magnitude. This hypothesis is used to generate dose-response curves describing the combined effects of epinephrine and theophylline, and these are compared with experimental data.

Download Full-text

A Systematic Method for Extracting Structural Parameters from Low Angle X-Ray Reflectivity Measurements on Multilayers

MRS Proceedings ◽

10.1557/proc-160-577 ◽

1989 ◽

Vol 160 ◽

Cited By ~ 3

Author(s):

L.M. Goldman ◽

H.A. Atwater ◽

F. Spaepen

Keyword(s):

External Surface ◽

Structural Parameters ◽

Structural Data ◽

X Ray Diffraction ◽

Systematic Method ◽

X Ray ◽

Dynamic Scattering

AbstractX-ray diffraction is one of the main methods of determining the structure of multilayers. Low angle reflectivity measurements are particulary useful for multilayers containing polycrystalline or amorphous constituents, and for obtaining specific structural data. We present a method based on both kinematic and dynamic scattering calculations, and use it to extract specific structural parameters such as the roughness or diffuseness of the external surface, the thickness of the constituent layers, and the roughness or diffuseness of the internal interfaces. Results are given for a sputtered A1/A12O3 multilayer.

Download Full-text

Studies on well-coupled Photosystem I-enriched subchloroplast vesicles. Neutral red as a probe for external surface charge rather than internal protonation

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/0005-2728(85)90064-7 ◽

1985 ◽

Vol 809 (2) ◽

pp. 204-214 ◽

Cited By ~ 16

Author(s):

Frits A. de Wolf ◽

Brenda H. Groen ◽

Leo P.A. van Houte ◽

Fons A.L.J. Peters ◽

Klaas Krab ◽

...

Keyword(s):

Surface Charge ◽

Photosystem I ◽

External Surface ◽

Neutral Red

Download Full-text

Selective block of calcium current by lanthanum in single bullfrog atrial cells.

The Journal of General Physiology ◽

10.1085/jgp.91.4.549 ◽

1988 ◽

Vol 91 (4) ◽

pp. 549-572 ◽

Cited By ~ 33

Author(s):

R D Nathan ◽

K Kanai ◽

R B Clark ◽

W Giles

Keyword(s):

Steady State ◽

Surface Charge ◽

Surface Potential ◽

Voltage Dependence ◽

External Surface ◽

Single Cells ◽

Ionic Currents ◽

Measurable Effect ◽

Nonspecific Effects ◽

Voltage Dependent

A single suction microelectrode voltage-clamp technique was used to study the actions of lanthanum ions (La3+) on ionic currents in single cells isolated from bullfrog right atrium. La3+, added as LaCl3, blocked the "slow" inward Ca2+ current (ICa) in a dose-dependent fashion; 10(-5) M produced complete inhibition. This effect was best fitted by a dose-response curve that was calculated assuming 1:1 binding of La3+ to a site having a dissociation constant of 7.5 x 10(-7) M. La3+ block was reversed (to 90% of control ICa) following washout and, in the presence of 10(-5) M La3+, was antagonized by raising the Ca2+ concentration from 2.5 to 7.5 mM (ICa recovered to 56% of the control). However, the latter effect took approximately 1 h to develop. Concentrations of La3+ that reduced ICa by 12-67%, 0.1-1.5 x 10(-6) M, had no measurable effect upon the voltage dependence of steady state ICa inactivation, which suggest that at these concentrations there are no significant surface-charge effects of La3+ on this gating mechanism. Three additional findings indicate that doses of La3+ that blocked ICa failed to produce nonspecific effects: (a) 10(-5) M La3+ had no measurable effect on the time-independent inwardly rectifying current, IK1; (b) the same concentration had no effect on the kinetics, amplitude, or voltage dependence of a time- and voltage-dependent K+ current, IK; and (c) 10(-4) M La3+ did not alter the size of the tetrodotoxin-sensitive inward Na+ current, INa, or the voltage dependence of its steady state inactivation. Higher concentrations (0.5-1.0 mM) reduced both IK1 and IK, and shifted the steady state activation curve for IK toward more positive potentials, presumably by reducing the external surface potential. Our results suggest that at a concentration of less than or equal to 10(-5) M, La3+ inhibits ICa selectively by direct blockade of Ca channels rather than by altering the external surface potential. At higher concentrations, La3+ exhibits nonspecific effects, including neutralization of negative external surface charge and inhibition of other time- and voltage-dependent ionic currents.

Download Full-text

Surface properties and clay mineralogy of hydrated halloysitic soil clays. I: Existence of interlayer K+ specific sites

Clay Minerals ◽

10.1180/claymin.1990.025.2.01 ◽

1990 ◽

Vol 25 (2) ◽

pp. 129-139 ◽

Cited By ~ 20

Author(s):

B. Delvaux ◽

A. J. Herbillon ◽

J. E. Dufey ◽

L. Vielvoye

Keyword(s):

Adsorption Isotherm ◽

Surface Charge ◽

Surface Properties ◽

External Surface ◽

Chloride Concentration ◽

Clay Mineralogy ◽

Internal Surface ◽

Surface Areas ◽

Soil Clays ◽

Tropical Conditions

AbstractSix deferrated clay (<2 µm) samples from the major B horizons of pedons derived from basaltic pyroclasts (Western Cameroon) were selected. These soil clays, which differ mainly in their contents of halloysite and kaolinite, represent the types of secondary constituents characteristic of different weathering stages in soils derived from such volcanic materials under humid tropical conditions. On these clays, Ca2+-K+ exchange equilibria were performed at pH 6 and 0·01 n chloride concentration. The amounts of K+ specific sites were estimated through a two-site modelling of the exchange isotherm curves. The total and external surface areas of the clays were measured by EGME retention and by the BET treatment of the N2 adsorption isotherm, respectively. Relative halloysite content was found to be directly related to all measured surface charge properties, i.e. CEC, amount of K+ specific sites, and total and internal surface areas. It was also observed that thermal collapse of halloysitic layers reduced both the CEC and the amount of K+ specific sites. All the surface properties observed point to the presence of smectite units intimately associated with halloysite in these clays. The results further suggest that the layer charge of these smectite units differs in different samples.

Download Full-text

Influence of the electret electric field on osteoreparation and inflammation in surgical treatment of simulated tuberculous osteitis estimated by morphological and biochemical criteria

MedAlliance ◽

10.36422/23076348-2020-8-4-46-58 ◽

2020 ◽

Vol 8 (4) ◽

pp. 46-58

Keyword(s):

Surgical Treatment ◽

Electric Field ◽

Surface Charge ◽

Bone Tissue ◽

External Surface ◽

Constant Electric Field ◽

Tantalum Oxide ◽

Activity Level ◽

Complete Regression ◽

Intact Group

Introduction. Recent trends in orthopedic surgery target factors and conditions that affect the destructive process-es in bone tissue and the effectiveness of reconstructive surgery. Electrets based on anodic tantalum oxide with negative external surface charge (hereinafter, “electret”) create a quasi-static long-term electric field in the sur-rounding space. Their implantation in the surgical treat-ment of early stages of degenerative joint diseases is accompanied by pronounced analgesic effect and signi-ficant increase in the quality of life of patients. Objective.To identify the features of osteogenesis and regression of specific inflammation in the surgical treatment of ex-perimental tuberculous osteitis in a constant electric field created by electret. Materials and methods. We studied the processes of osteoreparation and dynamics of the bone tissue specific inflammation activity in 30 rabbits with simulated tuberculous osteitis of the distal (meta-diaphysis) femur. 3 animals were intact (group 1), 6 rab-bits did not receive any therapy after tuberculous oste-itis simulation (group 2), 9 rabbits (group 3) underwent necrectomy and osteoplasty with autograft, 9 rabbits (group 4) underwent necrectomy and electret implanta-tion (with further generation of quasi-static electric field), and 6 animals (group 5) underwent necrectomy, osteo-plasty with autograft and perifocal electret implantation. Animals in groups 3, 4 and 5 received antituberculous therapy. The observation period was 1, 2 and 4 months after the grafting procedure. Bone regeneration and in-flammation regression were assessed with morphologi-cal and biochemical methods (enzymes of the purinergic system — activity of total adenosine deaminase and its isoenzymes, elastase activity, level of acute phase reac-tants: ceruloplasmin, haptoglobin, α1-acid glycoprotein, and albumin). Results. The evolution of tuberculous in-flammation of bone tissue was observed for the control periods in animals with simulated tuberculous osteitis. The analysis of bone tissue reparation and inflammation activity regression showed that only a combination of antituberculosis therapy, necrectomy, osteoplasty with autograft and electret perifocal implantation allowed in 2 months to achieve complete regression of active tuber-culosis and replacement of defect with mature trabec-ular bone. Conclusion. The electret electric field based on anodic tantalum oxide with negative external surface charge accelerates the processes of osteoreparation and reduces the activity of tuberculous inflammation in the surgical treatment of experimental tuberculous osteitis.

Download Full-text

Effects of external protons on single cardiac sodium channels from guinea pig ventricular myocytes.

The Journal of General Physiology ◽

10.1085/jgp.98.6.1065 ◽

1991 ◽

Vol 98 (6) ◽

pp. 1065-1083 ◽

Cited By ~ 30

Author(s):

J F Zhang ◽

S A Siegelbaum

Keyword(s):

Surface Charge ◽

Single Channel ◽

Ventricular Myocytes ◽

External Surface ◽

Current Amplitude ◽

H Infinity ◽

Channel Current ◽

Single Channel Current ◽

Negative Surface ◽

Negative Surface Charge

The effects of external protons on single sodium channel currents recorded from cell-attached patches on guinea pig ventricular myocytes were investigated. Extracellular protons reduce single channel current amplitude in a dose-dependent manner, consistent with a simple rapid channel block model where protons bind to a site within the channel with an apparent pKH of 5.10. The reduction in single channel current amplitude by protons is voltage independent between -70 and -20 mV. Increasing external proton concentration also shifts channel gating parameters to more positive voltages, consistent with previous macroscopic results. Similar voltage shifts are seen in the steady-state inactivation (h infinity) curve, the time constant for macroscopic current inactivation (tau h), and the first latency function describing channel activation. As pHo decreases from 7.4 to 5.5 the midpoint of the h infinity curve shifts from -107.6 +/- 2.6 mV (mean +/- SD, n = 16) to -94.3 +/- 1.9 mV (n = 3, P less than 0.001). These effects on channel gating are consistent with a reduction in negative surface potential due to titration of negative external surface charge. The Gouy-Chapman-Stern surface charge model incorporating specific proton binding provides an excellent fit to the dose-response curve for the shift in the midpoint of the h infinity curve with protons, yielding an estimate for total negative surface charge density of -1e/490 A2 and a pKH for proton binding of 5.16. By reducing external surface Na+ concentration, titration of negative surface charge can also quantitatively account for the reduction in single Na+ channel current amplitude, although we cannot rule out a potential role for channel block. Thus, titration by protons of a single class of negatively charged sites may account for effects on both single channel current amplitude and gating.

Download Full-text

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066097 ◽

1971 ◽

Vol 29 ◽

pp. 410-411 ◽

Cited By ~ 1

Author(s):

Jane A. Westfall ◽

S. Yamataka ◽

Paul D. Enos

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Osmium Tetroxide ◽

External Surface ◽

Three Dimensional ◽

Surface Structures ◽

Transmission Microscopy ◽

Transmission Electron ◽

Freeze Dried ◽

Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

Download Full-text

Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086180 ◽

1991 ◽

Vol 49 ◽

pp. 376-377 ◽

Cited By ~ 1

Author(s):

N.J. Tao ◽

J.A. DeRose ◽

P.I. Oden ◽

S.M. Lindsay

Keyword(s):

Surface Charge ◽

Environmental Effects ◽

Scanning Probe Microscopy ◽

Statistical Significance ◽

Electrochemical Methods ◽

Surface Structures ◽

Scanning Probe ◽

Potential Control ◽

Afm Imaging ◽

Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

Download Full-text

Tubulin structure at intermediate resolution

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100140634 ◽

1995 ◽

Vol 53 ◽

pp. 852-853

Author(s):

K. H. Downing ◽

S. G. Wolf ◽

E. Nogales

Keyword(s):

High Resolution ◽

Structural Data ◽

Therapeutic Drug ◽

Zinc Ions ◽

Two Dimensional ◽

X Ray Diffraction ◽

X Ray ◽

Negative Stain ◽

Functional Mechanisms ◽

Tubulin Structure

Microtubules are involved in a host of critical cell activities, many of which involve transport of organelles through the cell. Different sets of microtubules appear to form during the cell cycle for different functions. Knowledge of the structure of tubulin will be necessary in order to understand the various functional mechanisms of microtubule assemble, disassembly, and interaction with other molecules, but tubulin has so far resisted crystallization for x-ray diffraction studies. Fortuitously, in the presence of zinc ions, tubulin also forms two-dimensional, crystalline sheets that are ideally suited for study by electron microscopy. We have refined procedures for forming the sheets and preparing them for EM, and have been able to obtain high-resolution structural data that sheds light on the formation and stabilization of microtubules, and even the interaction with a therapeutic drug.Tubulin sheets had been extensively studied in negative stain, demonstrating that the same protofilament structure was formed in the sheets and microtubules. For high resolution studies, we have found that the sheets embedded in either glucose or tannin diffract to around 3 Å.

Download Full-text