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R Craig

Publications and source records attributed to R Craig.

At least 145 records · Page 8Linked to original sources
PubMed1977

Assembly of smooth muscle myosin into side-polar filaments.

The in vitro assembly of myosin purified from calf aorta muscle has been studied by electron microscopy. Two types of filament are formed: short bipolar filament similar to those formed from skeletal muscle myosin, and longer "side-polar" filaments having cross bridges with a single polarity along the entire length of one side and the opposite polarity along the other side. Unlike the case with skeletal myosin filaments, antiparallel interactions between myosin molecules occur along the whole length of side-polar filaments. The side-polar structure may be related to the in vivo form of myosin in vertebrate smooth muscle.

Animals↗
PubMedDate not supplied

Formulation and application of a numerical scoring system for assessing histological activity in asymptomatic chronic active hepatitis.

A Histology Activity Index has been developed which generates a numerical score for liver biopsy specimens obtained from patients with asymptomatic chronic active hepatitis. Biopsies are graded in four categories: periportal necrosis, intralobular necrosis, portal inflammation, and fibrosis. Under code, three pathologists and three hepatologists evaluated 14 liver biopsy specimens obtained from five patients with asymptomatic chronic active hepatitis. Good correlation was seen between severity of liver biopsy lesions as judged by conventional histological descriptions and Histology Activity Index scores. Significant differences in Histology Activity Index score occurred in only 2 or 28 duplicate scorings of biopsy specimens by two observers. This system provides definitive endpoints for statistical analysis of serial changes in liver histology and offers an alternative to the use of conventional pathological descriptions in following the natural history and treatment responses of asymptomatic chronic active hepatitis.

Biopsy↗
PubMedDate not supplied

Direct visualization of myosin filament symmetry in tarantula striated muscle by electron microscopy.

Chemically demembranated bundles of fibers from tarantula leg muscle were rapidly frozen in the relaxed state and freeze-substituted in the presence of tannic acid. Electron micrographs of thin transverse sections of freeze-substituted specimens frequently showed four clear, regularly organized projections (crossbridges) protruding from the backbones of the myosin filaments and partially wrapping around the filament surface. The rotational power spectra of individual filaments showed a peak at N = 4. Alignment and averaging of the images using correlation methods confirmed the fourfold symmetry and the slewed configuration of the crossbridges on the filament surface. These observations directly reveal essential features of the low-resolution three-dimensional helical reconstruction of negatively stained tarantula filaments calculated previously (R. A. Crowther, R. Padrón, and R. Craig, 1985, J. Mol. Biol. 184, 429-439).

Animals↗
PubMedDate not supplied

Three-dimensional reconstruction of thick filaments from rapidly frozen, freeze-substituted tarantula muscle.

We have applied three-dimensional helical reconstruction techniques to images of myosin filaments of tarantula leg muscle obtained from rapidly frozen, freeze-substituted specimens. Computed Fourier transforms of filaments selected from longitudinal sections show up to six layer lines indexing on the 43.5-nm helical repeat of myosin crossbridges. The three-dimensional reconstruction, performed after separation of overlapped Bessel functions, shows four continuous strands of density on the surface of the filament, modulated by density at 14.5-nm intervals, corresponding to the myosin heads aligned approximately along the helical strands. In transverse viw, the reconstruction shows four projections and is similar in profile to myosin filaments seen in thin transverse sections of rapidly frozen muscle. The reconstruction is similar to that of negatively stained, isolated tarantula filaments except that in the latter there is an additional modulation of the helix density, which better resolves the two heads of each myosin crossbridge. Thus, the general arrangement of the myosin heads in the freeze-substituted specimens is preserved, although finer details of structure such as individual myosin heads are lost.

Actin Cytoskeleton↗
PubMedDate not supplied

CT of calcified bladder masses.

Calcifications observed in bladder lesions are seen on plain films with an incidence of 0.5-7.0%. Four cases of calcification were noted on CT in 38 consecutive bladder scans (10.5%). Calcifications were noted both on the surface, and within the lesions. One of the cases with malakoplakia had calcification. This has not been reported to date. With CT, it is expected that calcification in bladder lesions will be found with increasing incidence, and should be looked for.

Aged↗
PubMedDate not supplied

Visualization of myosin helices in sections of rapidly frozen relaxed tarantula muscle.

Tarantula leg muscles in the relaxed state were rapidly frozen against a copper block cooled with liquid helium. Thin longitudinal sections of freeze-substituted specimens, both live and skinned, clearly showed the helical tracks of crossbridges on the surface of the myosin filaments, which are not preserved by conventional fixation. Fourier transforms of selected filaments showed a myosin layer line pattern, similar to that observed in X-ray diffraction patterns of intact tarantula muscle, extending to the sixth order of the 43.5 nm X-ray repeat. The phases of corresponding reflections were similar on the two sides of the meridian on the first layer line, and the crossbridge arrangement showed a line of mirror symmetry running down the center of the filament. These observations show that the number of helices (N) is even, in agreement with N = 4 determined from image analysis of negatively stained, isolated tarantula filaments (Crowther et al., J. Mol. Biol. 184, 429-439, 1985). Filtered images showed clear detail of the crossbridge helices and were similar to filtered images of negatively stained, isolated thick filaments. Thus, rapid freezing combined with freeze-substitution preserves the crossbridges in a three-dimensional arrangement approximating that occurring in vivo.

Animals↗
PubMedDate not supplied

Implementation of an algorithm for modeling disulfide bond patterns using mass spectrometry.

The paper describes the implementation of a software system based on the Fenyö disulfide bond assignment algorithm. The system allows an investigator to enter data derived from mass spectrum peak assignments, a target protein sequence and other experimental conditions. The output of the system is the set of disulfide bonding pattern models that are consistent with the experimental evidence. The software and code are available through a public web site, which also has a functioning, publicly accessible version of the disulfide bond modeler. This implementation was tested as part of a project to check homology-based assignments disulfide bonding patterns of human integrins.

Algorithms↗