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At least 19 recordsLinked to original sources
PubMed1991

Nebulin as a length regulator of thin filaments of vertebrate skeletal muscles: correlation of thin filament length, nebulin size, and epitope profile.

Nebulin, a family of giant proteins with size-variants from 600 to 900 kD in various skeletal muscles, have been proposed to constitute a set of inextensible filaments anchored at the Z line (Wang, K., and J. Wright. 1988. J. Cell Biol. 107:2199-2212). This newly discovered filament of the skeletal muscle sarcomere is an attractive candidate for a length-regulating template of thin filaments. To evaluate this hypothesis, we address the question of coextensiveness of nebulin and the thin filament by searching for a correlation between the size of nebulin variants and the length distribution of the thin filaments in several skeletal muscles. A positive linear correlation indeed exists for a group of six skeletal muscles that display narrow thin filament length distributions. To examine the molecular and architectural differences of nebulin size-variants, we carried out immunoelectron microscopic studies to map out epitope profiles of nebulin variants in these muscles. For this purpose, a panel of mAbs to distinct nebulin epitopes was produced against rabbit nebulin purified by an improved protocol. Epitope profiles of nebulin variants in three skeletal muscles revealed that (a) nebulin is inextensible since nebulin epitopes maintain a fixed distance to the Z line irrespective of the degree of sarcomere stretch; (b) a single nebulin polypeptide spans a minimal distance of 0.9 microns from the Z line; (c) nebulin contains repeating epitopes that are spaced at 40 nm or its multiples; (d) nebulin repeats coincide with thin filament periodicity; (e) nebulin variants differ mainly at either or both ends; and (f) nebulin remains in the sarcomere in actin-free sarcomeres produced by gelsolin treatment. Together, these data suggest that nebulin is an inextensible full-length molecular filament that is coextensive with thin filaments in skeletal muscles. We propose that nebulin acts as a length-regulating template that determines thin filament length by matching its large number of 40-nm repeating domains with an equal number of helical repeats of the actin filaments.

Animals↗
PubMed1989

Caldesmon and the structure of smooth muscle thin filaments: immunolocalization of caldesmon on thin filaments.

Antibodies reacting with chicken gizzard caldesmon were used to determine the distribution of caldesmon on smooth muscle thin filaments. Antibodies developed against both the intact caldesmon molecule and a 40 kilodalton proteolytic fragment cause thin filaments to aggregate laterally. Aggregates produced with the latter antibody display regular periodic labelling with a repeat of approximately 38 nm, a distribution characteristic of proteins associated with tropomyosin on thin filaments. The stoichiometry of caldesmon on thin filaments has been critically reevaluated and alternative models of caldesmon distribution on thin filaments are proposed.

Animals↗
PubMed1990

Caldesmon and the structure of smooth muscle thin filaments: electron microscopy of isolated thin filaments.

Native and synthetic vertebrate smooth muscle thin filaments have been examined by electron microscopy in order to determine the arrangement of the regulatory protein caldesmon. In synthetic filaments of actin-caldesmon, long slender molecules were sometimes seen running along the thin filament, suggesting that caldesmon can associate with actin along its length, while at other times lateral projections were observed. In native filaments, containing actin, caldesmon and tropomyosin, we found no evidence for lateral projections extending from the filaments, suggesting that caldesmon does not act as a crosslinking protein in vivo. In contrast, elongated molecules were clearly seen following the long pitch actin helices. We suggest that these may represent an association of caldesmon and tropomyosin. Antibodies developed against an N-terminal fragment of caldesmon caused thin filaments to aggregate laterally into arrays displaying approximately 35-38 nm repeats; thin filament aggregates with this periodicity were obtained previously (Lehman et al., 1989) using antibodies to the C-terminal segment of caldesmon. These results suggest that both ends of caldesmon are closely associated with the shaft of the thin filament, supporting a model in which the elongated caldesmon molecule runs along the filament, possibly interacting with tropomyosin, following the long pitch actin helices.

Animals↗
PubMed1991

The expression of actin mRNA in megakaryocytes demonstrated in paraffin sections, and epoxy resin semi-thin and thin sections by in situ hybridization.

Megakaryocytes of dog bone marrow were utilized as target cells for identifying actin mRNA expressing cells on semi-thin and thin sections. After in situ hybridization with radioisotope-labeled probes was performed on paraffin sections, gelatin capsules containing freshly prepared epoxy resin were placed on the sections. The resin was solidified and detached from the slide glass, and semi-thin and thin sections were obtained. The signals showing actin mRNA expression were detected on megakaryocytes in these sections by light and electron microscopy.

Actins↗
PubMed1991

[Retinol Acetate Reference Standard for Thin-layer Chromatography (Control 901) and Retinol Palmitate Reference Standard for Thin-layer Chromatography (Control 901) of National Institute of Hygienic Sciences].

The raw materials of retinol acetate and retinol palmitate were examined for the preparation of the "Retinol Acetate Reference Standard for Thin-layer Chromatography" and "Retinol Palmitate Reference Standard for Thin-layer Chromatography", respectively. Analytical data obtained were as follows: thin-layer chromatography, no impurities were detected in retinol acetate and one impurities was detected in retinol palmitate; The Rf values of retinol acetate and retinol palmitate were consistent with those of Reference Standards (Control 713), respectively; ultraviolet spectrum, lambda max = 326 approximately 327 nm; relative extinction, within the range reported in JPXI; weight variation of capsules, retinol acetate 224.0 +/- 15.5 mg (RSD 6.9%), retinol palmitate 222.0 +/- 13.8 mg (RSD 6.2%); assay, retinol acetate 57000 I.U./g, retinol palmitate 57000 I.U./g. Based on the above results, these raw materials were authorized to be the Reference Standards of the National Institute of Hygienic Sciences.

Chromatography, Thin Layer↗
PubMed1978

Birefringence of oriented thin filaments in the I-bands of crab striated muscle and comparison with the flow birefringence of reconstituted thin filaments.

Birefringence of the I-band of glycerinated myofibrils of the walking legs of the crab, Plagusia dentipes was examined by rectified polarization optics. The coefficient of birefringence of the I-band was estimated to be 1.64 X 10(-3), which attained about 60% of the birefringence of the H-zone. The number ratio of thin filaments to thick filaments in the A-band was six according to electron microscopy and the spacing between neighbouring thick filaments was about 56 nm according to X-ray diffraction. From these values, the protein concentration in the I-band was estimated to be 91 mg/ml. Thus, the birefringence of the I-band was found to be of the same order as the birefringence of the reconstituted thin filaments oriented by flow at the same protein concentration. The ratio of protein concentration in the I-band to that in the H-zone was determined by interferometry. The ratio of birefringence of the I-band to that of the H-zone per unit protein concentration was found to be about 0.9, which was comparable to the ratio of birefringence of the thin filaments and thick filaments in solution. The imbibition experiment showed that 70% of the total birefringence of the I-band is form birefringence and remaining 30% comes from intrinsic birefringence.

Animals↗
PubMed1979

[Studies on the thinning of the upper acrylic resin complete denture with the reinforced palate. (Part 1). Thinning of the resin denture base with the standard shape (author's transl)].

The acrylic denture bases are most commonly used as compared with metallic denture bases at present. For this reason, it is due to many excellent properties, for example, simple processing, easy repair, cheapness and so on. But an inherent disadvantage is liability of an acrylic denture base to make thick so as to maintain stiffness and strength and it makes patients uncomfortable. Therefore, the purpose of this paper is to make the palatal region of the upper complete denture thin with about 0.7 mm in thickness, and to keep the same mechanical properties as the normal resin dentures using the composites materials with carbon cloth. Tensils test of the plate test-piece and uniform bending test of the upper complete denture with steel wings were respectively performed. The results obtained in this investigation are as follows: 1) The acrylic composites reinforced with carbon cloth have shown the superior mechanical properties to be compared with the acrylic resin to be generally used. 2) The thickness of the reinforced thin denture is decreased to 0.7 mm (its thickness is 60% of the normal thickness of the one), nevertheless, the stiffness and strength are increased with the using of the composite materials. 3) The region of highest surface tensile stress in the denture was on the polished surface of the palatal aspect of the denture in the area immediately behind the anteriors, but at this region, the strain of the reinforced thin denture base decreased its strain 10% in comparison with the non-reinforced normal thick one.

Acrylic Resins↗
PubMed1977

[The quantitative detection of estrogens and antithyroid drugs by thin-layer and high performance thin-layer chromatography in animal tissue (author's transl)].

Methods of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) were developed for the determination of estrogens and antithyroid drugs in extracts of animal tissues. TLC proved to be suitable for quantities in the range of 200-2000 ng, with a detection limit of 50-200 ng, HPTLC in the range of 10-200 ng, showing calibration curves of good linearity even in extracts. By HPTLC better detection limits, better separation and faster ascending could be achieved than by TLC.

Animals↗
PubMed1979

Quantitative thin-layer chromatography: thin-film fluorescence scanning analysis of adriamycin and metabolites in tissue.

A rapid, non-hydrolytic thin-film fluorescence scanning method is described for the quantitation of adriamycin and metabolites in tissues. Adriamycin, with daunomycin added as the internal standard, was extracted from tissue homogenate which contained 500 micrograms of oxalic acid, with ice-cold 0.5 N hydrochloric acid--85% isopropanol, separated by thin-layer chromatography, and quantitated in situ via a fluorescence scanning technique. This method has a sensitivity to 0.05 microgram per gram of tissue.

Animals↗
PubMedDate not supplied

Evaluation of a multiple-variable thin-layer and reversed-phase thin-layer chromatographic scheme for identification of basic and neutral drugs in an emergency toxicology setting.

An analytical scheme composed of one normal-phase thin-layer chromatographic (TLC) method, one reversed-phase thin-layer chromatographic (RPTLC) method, and sequential analyte detection through four stages of color reactions is described. Eighty-one basic or neutral drugs were analyzed with this scheme and seventy-four were uniquely characterized with 95% confidence. Six of the remaining seven formed three unresolved pairs. The scheme was evaluated by mean list length analysis and shown to offer analyte resolution similar to that of a scheme of TLC and gas chromatography (GC) with nonspecific detection. Nine out of ten unknowns from the field of eighty-one drugs were uniquely identified with 95% confidence by the TLC/RPTLC scheme. The tenth unknown was not completely resolved from its isomer, but was statistically the more probable candidate.

Chromatography, Thin Layer↗
PubMed1990

Resonance energy transfer between points in a reconstituted skeletal muscle thin filament. A conformational change of the thin filament in response to a change in Ca2+ concentration.

The spatial relationships between Lys-61, Cys-374 on actin or SH1 on myosin subfragment-1 (S1) and Cys-190 on tropomyosin or Cys-133 on troponin-I (TnI) in a reconstituted thin filament were studied by fluorescence resonance energy transfer. 5-(2-Iodoacetylaminoethyl)aminonaphthalene 1-sulfonic acid (IAEDANS) attached to Lys-190 on tropomyosin or to Cys-133 on TnI was used as a donor. Fluorescein 5-isothiocyanate (FITC) attached to Lys-61 or 5-(iodoacetoamido)fluorescein (IAF) attached to Cys-374 on actin and 4-dimethylaminophenyl-azophenyl 4'-maleimide (DABMI) attached to SH1 on S1 were used as an acceptor. The transfer efficiency between AEDANS attached to Cys-190 on tropomyosin and FITC attached to Lys-61 on actin was 0.42 in the absence of troponin, 0.46 in the presence of troponin and Ca2+ and 0.55 in the presence of troponin and absence of Ca2+. The corresponding distances between the probes were calculated to be 4.7 nm, 4.6 nm and 4.3 nm respectively, assuming a random orientation factor K2 = 2/3. A large difference in the transfer efficiency from AEDANS attached to Cys-133 on TnI to FITC attached to Lys-61 on actin was observed between in the presence (0.52) and absence (0.70) of Ca2+. The corresponding distances between the probes were calculated to be 4.5 nm in the presence of Ca2+ and 3.9 nm in the absence of Ca2+. The distance between Cys-190 on tropomyosin and Cys-374 on actin was measured to be 5.1 nm and the transfer efficiency (0.35) did not change upon addition of troponin whether Ca2+ is present or not, in agreement with the previous report [Tao, T., Lamkin, M. & Lehrer, S. S. (1983) Biochemistry 22, 3059-3064]. The distance between Cys-133 on TnI and Cys-374 on actin was measured to be 4.4 nm. No detectable change in transfer efficiency (0.58) was observed between values in the presence and absence of Ca2+. These results suggest that a relative movement of the two domains of actin monomer in a reconstituted thin filament occurs in response to a change in Ca2+ concentration. The transfer efficiencies between DABMI attached to SH1 on S1 and AEDANS attached to Cys-190 on tropomyosin or Cys-133 on TnI were too small (less than 2%) for an accurate estimation of the distances, suggesting the distances are longer than 7.3 nm.

Actins↗
PubMed1978

SGC (small granule chromaffin) cells in the mouse adrenal medulla: light and electron microscopic identification using semi-thin and ultra-thin sections.

Adrenal glands of the mouse, fixed either in glutaraldehyde followed by osmium tetroxide or in a mixture of potassium dichromate and glutaraldehyde, and embedded in Epon 812, were investigated by light and electron microscopy. An argentaffin reaction was applied to semi-thin sections for light microscopy and to ultra-thin sections for electron microscopy. Since the mature secretory granules in the Small Granule Chromaffin (SGC) cell were argentaffin and were mainly located along the cell membrane, this cell was clearly distinguishable under the light microscope both from the A (adrenaline) cell whose secretory granules were non-argentaffin and from the NA (noradrenaline) cell whose cytoplasm was rich and was filled with large, strongly argentaffin granules. Chromaffinity of the SGC cell was demonstrated under the light microscope. The SGC cell was intensively stained with toluidine blue without revealing metachromasia. It was demonstrated at the EM level that not only the secretory granules but also the synaptic-like vesicles in the SGC cell contained argentaffin substances. Possible functional relationship between the secretory granules and the synaptic-like vesicles was discussed.

Adrenal Medulla↗
PubMed1975

Use of combined chromatographic methods including thin-layer chromatography for analysis of complex polymer systems. Determination of the polydispersity of block copolymers of styrene and methyl methacrylate by gel permeation, thin-layer and pyrolysis gas chromatography.

A combination of gel permeation chromatography (GPC), thin-layer chromatography (TLC) and pyrolysis gas chromatography (PGC) has been used for investigations of a polymethyl methacrylate-polystyrene-polymethyl methacrylate block copolymer. Continuous distribution of the polymer (40-mg sample) was attained according to the content of the styrene and methyl methacrylate units and of the block copolymer and according to the composition of the copolymer as functions of the hydrodynamic radius of the macromolecules. The polymer was subjected to a preliminary fractionation with an analytical gel chromatograph. The fractions were investigated by TLC, which permitted the separation of the block copolymer and the homopolymers. The composition of the fractions obtained by GPC and TLC was determined by PGC. As a result, it was possible to establish the composition of the block copolymer and its ratio to polymethyl methacrylate in each fraction. This investigation was based on a combination of highly effective fractionation by chromatographic methods with precise quantitative ratios obtained from Benoit's universal calibration graph and from determinations of the composition of the polymer fractions by PGC. The mechanism of the TLC of polymers, including the appearance of artefacts that distort the results of analysis, is also discussed.

Chromatography↗
PubMed1975

Improvements in the thin-layer chromatography of natural products. I. Thin-layer chromatography of the aflatoxins.

During the period which has elapsed since the aflatoxins were first isolated, one of the main problems has been the separation of the individual aflatoxins in pure form from aflatoxin-containing extracts. This separation has been best effected by thin-layer chromatography, and in this paper we describe how some of the difficulties may be overcome by using an appropriate combination of solvent system and silica gel preparation. For the examination of aflatoxin-containing extracts from the mycelia of Aspergillus flavus moulds, an initial freeze-drying step has been found to improve appreciably the quality of the chromatograms obtained.

Acetates↗
PubMed1975

An improved technique for the analysis of amino acids and related compounds on thin layers of cellulose. X. The characterization of some methionyl, phenylalanyl, tyrosyl and other peptides by thin-layer and ion-exchange chromatography.

This paper is a continuation of previous work (Parts VI, VIII, and IX) designed to identify small peptides in biological fluids by a combination of ion-exchange and thin-layer chromatography. Several series of peptides, mainly dipeptides, with methionine, phenylalanine, tyrosine, aspartic acid, serine, or glutamic acid as the N-terminal amino acid, have been examined.

Amino Acids↗
PubMed1977

Quantitation with high-performance thin-layer chromatography and programmed multiple development with high-performance micro-thin-layer material for drug analyses in biological fluids.

The programmed multiple development thin-layer chromatography (PMD-TLC) technique was compared with the conventional chromatographic technique on both normal and HPTLC plates. The potency of this high-performance TLC is illustrated and discussed by means of the data obtained with the determination of digitoxin in human serum. Improvement of the efficiency of TLC, resulting in a better resolution and sensitivity with PMD-TLC using using HPTLC plates, makes this high-performance TLC technique comparable to high-performance liquid chromatography. This TLC approach might lead to a sensitive, rapid, selective and simply assay for routine serial analyses and, because of its specificity and flexibility, it may facilitate drug interaction studies.

Chromatography, High Pressure Liquid↗