Alterations of the perivascular dystrophin-dystroglycan complex following brain lesions: an immunohistochemical study in rats.

Dystroglycan is a laminin receptor, which with dystrophins and other components forms the dystrophin-dystroglycan complex. It has an important role in the formation of gliovascular connections, cerebral vascularisation and blood-brain barrier. Dystroglycan consists of two sub-units, α and ß. Previous studies demonstrated that the ß-dystroglycan immunoreactivity of cerebral vessels temporarily disappeared in the area adjacent to the lesion, whereas the vascular laminin which is not immunoreactive in the intact brain became detectable. The present study extends these investigations over other components of the complex: utrophin, α1-syntrophin and α1-dystrobrevin. The experiments were performed on adult rats. The lesions were stab wounds or cryogenic lesions in deep ketamine-xylasine narcosis. Following survival periods 2 to 30 days, the animals were perfused and floating brain sections were processed for fluorescent immunohistochemistry. The α1-dystrobrevin, like ß-dystroglycan, vanished temporarily around the lesion. The immunoreactivity of utrophin changed in a similar way to that of laminin. In intact brains they were confined to the entering segments of the vessels and to the circumventricular organs. Following lesions their immunoreactivity manifested in the vessels around the lesions. However, utrophin followed laminin with a delay: their peaks were about POD (postoperative days) 21 and 7, respectively. Only immunoreactivity of α1-syntrophin appeared in the reactive astrocytes, peaking at POD 14. Double-labeling proved its co-localization with GFAP. Cryogenic lesions had similar immunohistochemical effects, but provided more suitable samples for Western blot analysis, which proved the altered levels of α1-dystrobrevin and α1-syntrophin. The phenomena may help to monitor the post-lesion vascular processes and the alterations of the gliovascular connections.

One nanosecond photon correlation spectroscopy on smectic liquid crystal films.

We have extended photon correlation spectroscopy down to a one-nanosecond time scale, and applied it to a study of layer undulations in freestanding smectic-A films of two cyanobiphenyl liquid crystals. Temporal correlations in the intensity of scattered light reveal an interesting combination of under- and overdamped modes. The underdamped mode is accurately described by a recently calculated correlation function of the smectic layer displacement, although its frequency and damping rate exhibit stronger dispersion at large optical wave vectors than expected from current dynamical models for smectic films.

Light scattering study of a twist grain boundary liquid crystal.

Dynamic light scattering is used to probe the fluctuation modes of a liquid crystal exhibiting twist grain boundary (TGB) structure. At the chiral nematic to proposed "chiral line liquid" phase transition, anomalous temperature dependence in the fluctuation spectrum and an instability in the helicoidal director structure signify developing TGB order. At lower temperatures, the behavior of the smectic layer-director fluctuations ("soft" mode) indicates that the previously identified commensurate TGB(A) phase may in fact be a TGB(C) phase with an unusually small tilt angle.

Dynamics of the nematic phase of a bent-core liquid crystal.

The dielectric fluctuations in the uniaxial nematic phase of a bent-core liquid crystal have been studied by dynamic light scattering. Polarization selection of the scattering cross-section reveals one mode due to ordinary director fluctuations and, in the lower part of the nematic phase, a second mode attributable to fluctuations of the biaxial order parameter. The director fluctuations are approximately 100 times slower than observed in typical nematics based on straight-core molecules, suggesting that the bent core nematogenic units may be microscopic smectic domains ("cybotactic" clusters).

Particle sizing in strongly turbid suspensions with the one-beam cross-correlation dynamic light-scattering technique.

The utility of the one-beam cross-correlation dynamic light-scattering system for sizing small particles in suspension was previously limited by its small-intensity signal-to-baseline ratio for strongly turbid suspensions. We describe three improvements in the optical system and sample cell that raise the ratio to a value comparable with that of other cross-correlation dynamic light-scattering systems. These improvements are (i) using a square cross-sectional sample cell to minimize the attenuation of the incident beam and singly scattered light, (ii) placing a 200-microm-wide slit between the sample cell and the detector fibers to mask off the region of weak single scattering and strong multiple scattering from the detectors' field of view, and (iii) aligning the center of the detectors' field of view with the region of strongest single scattering. We analyze a number of suspensions of polystyrene latex spheres with a diameter between 65 and 562 nm in water using this improved one-beam instrument and find that the measured radius is determined in a 2-min data collection time to better than +/-10% for volume fractions of the suspended polystyrene latex spheres up to a few percent.

[Analysis of radiographic changes in the cervical spine in rheumatoid arthritis]. / A nyaki gerinc röntgen tüneteinek elemzése rheumatoid arthritisben.

At the outpatient department of rheumatology 100 patients having definitive or classic rheumatoid arthritis (RA) were examined and their cervical spine was radiographed with traditional X-ray technique. Correlation between roentgen signs and some parameters of the patient and of the disease was processed by regression analysis. The presence of the rheumatoid factor and second line drug therapy did not influence radiographic changes. Degenerative roentgen signs showed a linear correlation with the RA functional capacity and the duration of cervical complaints, and an exponential correlation with the duration of disease and the age of the patient. There was a linear correlation between osteoporosis and all the parameters examined. Inflammatory radiographic changes showed an exponential correlation with functional capacity and duration of cervical complaints, and a linear correlation with the duration of illness and the age of the patient. Symptoms of patients never treated with steroids was more severe than of those receiving short steroid therapy, but less serious than of those who had taken steroids for a long time (for longer than 10 years).

Hypertrophic osteoarthropathy associated with alcoholic liver disease without cirrhosis.

Two cases of secondary hypertrophic osteoarthropathy associated with alcoholic liver disease without cirrhosis are reported. Conditions which can be associated with hypertrophic osteoarthropathy and theoretical factors which can play a role in its pathomechanism are briefly discussed.