scholarly journals ACETYL DISULFIDE, (CH3COS)2, AND BIS-(THIOACETOXY) AURATE (I) COMPLEX, Au(CH3COS)2–, HISTOCHEMICAL SUBSTRATES OF UNUSUAL PROPERTIES WITH ACETYLCHOLINESTERASE

1968 ◽  
Vol 16 (12) ◽  
pp. 754-764 ◽  
Author(s):  
GEORGE B. KOELLE ◽  
RICHARD DAVIS ◽  
MARTINA DEVLIN
Keyword(s):  
Metal Ion ◽  
Histochemical Staining ◽  
Histochemical Reaction ◽  
Black Precipitate ◽  
Spontaneous Hydrolysis ◽  
Sigmoid Curve ◽  
Fine Localization ◽  
Thiolacetic Acid ◽  
Bell Shaped Curve ◽  
Supernatant Solution

The histochemical reaction for acetylcholinesterase (AChE) employing acetyl disulfide ([CH3COS]2, or AcDiS) as substrate and 0.006 M Pb(NO3)2 as capturing agent was characterized by (1) a sigmoid curve for velocity of hydrolysis versus substrate concentration and (2) a red precipitate (presumably [CH3COSS]2Pb) at sites of AChE at the motor endplates (MEP's) and (from spontaneous hydrolysis) in the supernatant solution. With the addition of 0.03 M thiolacetic acid (TA) to the incubation medium, which by itself produced little or no histochemical staining, the foregoing characteristics were changed to (1) a bell-shaped curve, with the peak at 0.003 M AcDiS, and (2) a black precipitate (presumably PbS) at the MEP's and in the supernatant solution; in addition, the velocity of hydrolysis was increased approximately 100-fold. Comparable differences were obtained with AcDiS as substrate when using ionic Au+ or Au(S2O3)2–3 as the capturing agent. Results are explained on the basis that in the absence of free heavy metal ion ( i.e., with the Pb[TA]2 or Au[S2O3]2–3 complex), AcDiS combines with AChE at both the anionic and esteratic sites, whereas, in the presence of Pb2+ or Au+, attachment of the substrate occurs only at the esteratic site of the enzyme. Results similar to the former type were obtained when the bis-(thioacetoxy) aurate (I) complex (Au[CH3COS]2– or Au[TA]2– served as both substrate and capturing agent. With both the AcDiS-Au(S2O3)2–3 and Au (TA)2– methods, extremely fine localization of AChE was obtained at the MEP's by electron microscopy.

scholarly journals Enzymatic Activity in the M Band

1959 ◽  
Vol 6 (2) ◽  
pp. 163-170 ◽  
Author(s):  
Russell J. Barrnett ◽  
George E. Palade
Keyword(s):  
Electron Microscopy ◽  
Enzymatic Hydrolysis ◽  
Enzymatic Activity ◽  
Striated Muscles ◽  
Histochemical Reaction ◽  
Esterase Inhibitors ◽  
Enzymatic Nature ◽  
Hydrolysis Of ◽  
Thiolacetic Acid

Experiments which combined histochemistry and electron microscopy were performed in studying the sites of enzymatic hydrolysis of thiolacetic acid in the presence of lead ions in diaphragmatic and cardiac muscle. It was found that in these striated muscles the electron opaque, final product of the histochemical reaction (PbS) was discretely deposited on the swelling of the thick elemental filaments that occurs at the M band. Additional sites of enzymatic activity occurred in mitrochondria and in round sarcoplasmic bodies. A reaction, probably non-enzymatic, also occurred in contraction bands in the area of the Z bands and in the sarcoplasmic reticulum. To ascertain the enzymatic nature of the reaction and to define the enzyme involved, control experiments were carried out and the effect of various esterase inhibitors was assayed. It is suggested that the M band enzyme is a cholinesterase, but the enzymes in the mitochondria and the sarcoplasmic bodies that hydrolyze the substrate appear to be different. A possible role of the M band enzyme is discussed.

HISTOCHEMICAL CHANGES IN THE OVARIES OF NORMAL AND EXPERIMENTALLY TREATED RATS

1961 ◽  
Vol 36 (3) ◽  
pp. 361-374 ◽  
Author(s):  
Fletcher B. Taylor
Keyword(s):  
Ovarian Tissue ◽  
Blood Stream ◽  
Histochemical Staining ◽  
Interstitial Tissue ◽  
List Type ◽  
Histochemical Reaction ◽  
Adult Rat ◽  
Immature Rats ◽  
Luteal Tissue ◽  
Histochemical Changes

ABSTRACT Results from histochemical staining of ovaries of normal and experimentally treated rats using a method allegedly specific for 3β-ol steroids, together with blood progestin, progesterone (pregn-4-ene-3,20-dione) and urine pregnanediol (5β-pregnane-3α-20α-diol) determinations suggested that: 1. Thecal and interstitial tissue as well as luteal tissue of adult rat ovaries all produced progesterone and consequently the production of progesterone was not limited to a specific anatomic unit (e. g. corpus luteum). 2. The progesterone thus produced was secreted in part into the blood stream, for with each significant increase in the intensity of the histochemical reaction there was an associated rise in blood progestin, progesterone and urine pregnanediol. This did not quantitate the amount of progesterone involved in intermediary metabolism (e. g. of allopregnane3β-ol-20-one, pregn-4-ene-3β-ol-20-one). 3. The ovarian tissue of immature rats also produced progesterone.

scholarly journals Histomorphometric identification of carbonic anhydrase in fetal rat bone embedded in glycolmethacrylate.

1987 ◽  
Vol 35 (2) ◽  
pp. 245-250 ◽  
Author(s):  
P J Marie ◽  
M Hott
Keyword(s):  
Acid Phosphatase ◽  
Carbonic Anhydrase ◽  
Bone Tissue ◽  
Specific Inhibitor ◽  
Slight Modification ◽  
Histochemical Staining ◽  
Histochemical Reaction ◽  
Low Concentrations ◽  
Fetal Rat ◽  
Rat Bone

Carbonic anhydrase was identified in bone-resorbing cells present in sections of fetal rat femur embedded in glycolmethacrylate. Using a slight modification of the Hansson's histochemical method, we demonstrated that most chondroclasts (91.8-95.4%) and osteoclasts (95.1-96.3%) display a positive histochemical reaction for carbonic anhydrase. This staining was consistently inhibited in the presence of very low concentrations (10(-6), 10(-7) M) of the specific inhibitor acetazolamide. The number of chondroclasts reacting for carbonic anhydrase was identical to the number of acid phosphatase-stained chondroclasts determined on adjacent sections. A large majority of osteoclasts (96.3%) stained for carbonic anhydrase and for acid phosphatase (97.2%), with more osteoclasts reacting for the latter enzyme than the former (76.8 +/- 8.5 (SD) vs 85.3 +/- 9.2 cells/mm2 of endosteal bone; p less than 0.01). The observation that acetazolamide at a concentration as low as 10(-7) M inhibited Hansson's reaction, together with our histomorphometric results, validates the use of histochemical staining for carbonic anhydrase to evaluate activity of bone-resorbing cells identified in plastic-embedded fetal bone tissue.

scholarly journals COMPLEX FORMATION BETWEEN HEAVY METALS AND THIOLACETIC ACID IN ELECTRON MICROSCOPIC HISTOCHEMISTRY

1965 ◽  
Vol 13 (7) ◽  
pp. 566-570 ◽  
Author(s):  
NIELS HAUGAARD ◽  
ROBERT S. HORN ◽  
GEORGE B. KOELLE
Keyword(s):  
Heavy Metals ◽  
Complex Formation ◽  
Metal Ions ◽  
Metal Ion ◽  
Bathochromic Shift ◽  
Ultraviolet Spectrum ◽  
Lead Ions ◽  
Electron Microscopic ◽  
Tissue Sections ◽  
Thiolacetic Acid

Evidence for the formations of complexes of aurous and lead ions with thiolacetic acid was obtained by two methods. (1) It was demonstrated that the addition of the metal ions to solutions of thiolacetic acid at pH 6.2 caused a bathochromic shift of the ultraviolet spectrum of this compound characteristic of those observed on combination of metal ions with an organic resonator. The experiments indicated that aurous ions form a coordinate complex with thiolacetic acid containing one metal ion and two thiolacetate residues. (2) It was observed that aurous and lead ions inhibited the reaction of thiolacetic acid with N-ethylmaleimide. Complex formation of the heavy metals with thiolacetic acid may be of importance in preventing their binding at nonspecific sites and in facilitating their penetration into tissue sections in the adaptation for electron microscopy of the thiolacetic acid method for cholinesterases.

Migraine Prescription Density and Recommendations. Results of the pcaom Study

Cephalalgia ◽  
1999 ◽  
Vol 19 (5) ◽  
pp. 511-519 ◽  
Author(s):  
KJ Krobot ◽  
HW Steinberg ◽  
V Pfaffenrath
Keyword(s):  
Primary Care ◽  
Statutory Health Insurance ◽  
Insurance Fund ◽  
Health Insurance Fund ◽  
Sigmoid Curve ◽  
Care Practices ◽  
Primary Care Practices ◽  
German Statutory Health Insurance ◽  
Statutory Health Insurance Fund ◽  
Bell Shaped Curve

We estimate the extent to which recommendations on the prevention and treatment of migraine issued by professional medical bodies are implemented in medical practice in Germany. Computerized data (MediPlus, IMS Health) were analyzed in 4,636 male and 16,573 female migraineurs from 383 primary care practices 1994 through 1996 (Primary Care of Migraine, PCAOM study). A total of 90,540 drug prescriptions with a documented diagnosis of migraine were issued in 45,669 person-years (1.492 prescriptions [DM 40.99] per person-year to men, 2.109 prescriptions [DM 62.01] per person-year to women). Approximately three of every four prescriptions were incompatible with the recommendations of the German Migraine and Headache Society (DMKG), amounting to extrapolated costs of DM 49 million per year borne by the German statutory health insurance fund for combination migraine preparations. The density of non-DMKG therapies for diagnosed migraine followed a sigmoid curve with increasing patient age, while DMKG-compliant therapies described a bell-shaped curve. Referrals to neurological care specialists were not associated with subsequent primary care focus on recommended therapies. We conclude that medication prescribed for migraine is largely not according to long-standing recommendations by medical societies in Germany.

Aspects of high-resolution imaging with a scanning ion microprobe

1986 ◽  
Vol 44 ◽  
pp. 750-751
Author(s):  
R. Levi-Setti ◽  
J. M. Chabala ◽  
Y. L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Chromatic Aberration ◽  
Ion Source ◽  
Ion Microprobe ◽  
Emission Pattern ◽  
Intrinsic Resolution ◽  
Resolution Imaging ◽  
20 Nm ◽  
Secondary Ion

We have shown the feasibility of 20 nm lateral resolution in both topographic and elemental imaging using probes of this size from a liquid metal ion source (LMIS) scanning ion microprobe (SIM). This performance, which approaches the intrinsic resolution limits of secondary ion mass spectrometry (SIMS), was attained by limiting the size of the beam defining aperture (5μm) to subtend a semiangle at the source of 0.16 mr. The ensuing probe current, in our chromatic-aberration limited optical system, was 1.6 pA with Ga+ or In+ sources. Although unique applications of such low current probes have been demonstrated,) the stringent alignment requirements which they imposed made their routine use impractical. For instance, the occasional tendency of the LMIS to shift its emission pattern caused severe misalignment problems.

Scanning ion microscopy images

1987 ◽  
Vol 45 ◽  
pp. 180-181
Author(s):  
R. Levi-Setti ◽  
J.M. Chabala ◽  
Y.L. Wang
Keyword(s):  
Metal Ion ◽  
Secondary Emission ◽  
Scanning Method ◽  
Ion Channeling ◽  
Secondary Ions ◽  
High Resolution Images ◽  
Ion Microscopy ◽  
Z Contrast ◽  
Focused Beams ◽  
Microscopy Images

Finely focused beams extracted from liquid metal ion sources (LMIS) provide a wealth of secondary signals which can be exploited to create high resolution images by the scanning method. The images of scanning ion microscopy (SIM) encompass a variety of contrast mechanisms which we classify into two broad categories: a) Emission contrast and b) Analytical contrast.Emission contrast refers to those mechanisms inherent to the emission of secondaries by solids under ion bombardment. The contrast-carrying signals consist of ion-induced secondary electrons (ISE) and secondary ions (ISI). Both signals exhibit i) topographic emission contrast due to the existence of differential geometric emission and collection effects, ii) crystallographic emission contrast, due to primary ion channeling phenomena and differential oxidation of crystalline surfaces, iii) chemical emission or Z-contrast, related to the dependence of the secondary emission yields on the Z and surface chemical state of the target.

Freeze-etch TEM of aqueous polymer gel network morphology

1986 ◽  
Vol 44 ◽  
pp. 796-797
Author(s):  
J. A. N. Zasadzinski ◽  
R. K. Prud'homme
Keyword(s):  
Metal Ion ◽  
Polymer Network ◽  
Polymer Gels ◽  
Polymer Gel ◽  
Deformation History ◽  
Crosslinked Polymer ◽  
Aqueous Polymer ◽  
History Of ◽  
Gel Network ◽  
Network Morphology

The rheological and mechanical properties of crosslinked polymer gels arise from the structure of the gel network. In turn, the structure of the gel network results from: thermodynamically determined interactions between the polymer chain segments, the interactions of the crosslinking metal ion with the polymer, and the deformation history of the network. Interpretations of mechanical and rheological measurements on polymer gels invariably begin with a conceptual model of,the microstructure of the gel network derived from polymer kinetic theory. In the present work, we use freeze-etch replication TEM to image the polymer network morphology of titanium crosslinked hydroxypropyl guars in an attempt to directly relate macroscopic phenomena with network structure.

Structures of c-di-GMP/cGAMP degrading phosphodiesterase VcEAL: identification of a novel conformational switch and its implication

2019 ◽  
Vol 476 (21) ◽  
pp. 3333-3353 ◽  
Author(s):  
Malti Yadav ◽  
Kamalendu Pal ◽  
Udayaditya Sen
Keyword(s):  
Active Site ◽  
Metal Binding ◽  
Metal Ion ◽  
Triosephosphate Isomerase ◽  
Catalytic Mechanism ◽  
Degradation Mechanism ◽  
Structural Basis ◽  
Conserved Residues ◽  
Phosphodiester Bond ◽  
Cyclic Dinucleotides

Cyclic dinucleotides (CDNs) have emerged as the central molecules that aid bacteria to adapt and thrive in changing environmental conditions. Therefore, tight regulation of intracellular CDN concentration by counteracting the action of dinucleotide cyclases and phosphodiesterases (PDEs) is critical. Here, we demonstrate that a putative stand-alone EAL domain PDE from Vibrio cholerae (VcEAL) is capable to degrade both the second messenger c-di-GMP and hybrid 3′3′-cyclic GMP–AMP (cGAMP). To unveil their degradation mechanism, we have determined high-resolution crystal structures of VcEAL with Ca2+, c-di-GMP-Ca2+, 5′-pGpG-Ca2+ and cGAMP-Ca2+, the latter provides the first structural basis of cGAMP hydrolysis. Structural studies reveal a typical triosephosphate isomerase barrel-fold with substrate c-di-GMP/cGAMP bound in an extended conformation. Highly conserved residues specifically bind the guanine base of c-di-GMP/cGAMP in the G2 site while the semi-conserved nature of residues at the G1 site could act as a specificity determinant. Two metal ions, co-ordinated with six stubbornly conserved residues and two non-bridging scissile phosphate oxygens of c-di-GMP/cGAMP, activate a water molecule for an in-line attack on the phosphodiester bond, supporting two-metal ion-based catalytic mechanism. PDE activity and biofilm assays of several prudently designed mutants collectively demonstrate that VcEAL active site is charge and size optimized. Intriguingly, in VcEAL-5′-pGpG-Ca2+ structure, β5–α5 loop adopts a novel conformation that along with conserved E131 creates a new metal-binding site. This novel conformation along with several subtle changes in the active site designate VcEAL-5′-pGpG-Ca2+ structure quite different from other 5′-pGpG bound structures reported earlier.

A Fast Histochemical Staining Method to Identify Hyaline Droplets in the Rat Kidney

2003 ◽  
Vol 31 (4) ◽  
pp. 462-464 ◽  
Author(s):  
Eveline P. C. T. de Rijk ◽  
Wilma T. M. Ravesloot ◽  
Yvonne Wijnands ◽  
Eric van Esch
Keyword(s):  
Staining Method ◽  
Rat Kidney ◽  
Histochemical Staining
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