A repeating fast radio burst source in a globular cluster.

Fast radio bursts (FRBs) are flashes of unknown physical origin1. The majority of FRBs have been seen only once, although some are known to generate multiple flashes2,3. Many models invoke magnetically powered neutron stars (magnetars) as the source of the emission4,5. Recently, the discovery6 of another repeater (FRB 20200120E) was announced, in the direction of the nearby galaxy M81, with four potential counterparts at other wavelengths6. Here we report observations that localized the FRB to a globular cluster associated with M81, where it is 2 parsecs away from the optical centre of the cluster. Globular clusters host old stellar populations, challenging FRB models that invoke young magnetars formed in a core-collapse supernova. We propose instead that FRB 20200120E originates from a highly magnetized neutron star formed either through the accretion-induced collapse of a white dwarf, or the merger of compact stars in a binary system7. Compact binaries are efficiently formed inside globular clusters, so a model invoking them could also be responsible for the observed bursts.

Compact radio emission indicates a structured jet was produced by a binary neutron star merger.

The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milli-arc seconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet.

Microfibrillar structure of PGG-glucan in aqueous solution as triple-helix aggregates by small angle x-ray scattering.

The conformation of polysaccharide PGG-Glucan, isolated from yeast cell walls, in aqueous solution was investigated by small angle x-ray scattering (SAXS) and multidetector gel permeation chromatography coupled with postcolumn delivery (GPC/PCD) techniques in comparison with scleroglucan. It was shown that both polysaccharides exhibit a rigid rod-like conformation in aqueous solution by SAXS experiments. The mass per unit length (M/L) and radius (R) of rod cross section of PGG-Glucan were measured to be 6300 daltons/nm and 1.89 nm, while those of scleroglucan are 2300 and 0.83, respectively. Utilizing a GPC/light scattering technique, the average aggregation number of PGG-Glucan is 9, while that of scleroglucan is around 3. From the comparison of the M/L and R of the respective rod cross sections as well as their aggregation number data, it is concluded that PGG-Glucan is composed of triple helices, which tend to aggregate as triplets in solution, whereas scleroglucan is composed of a single triple helix. The aggregation number distribution of PGG-Glucan was found to range from 1 to about 25 determined by GPC/PCD. From the observation of a Debye-Scherrer ring type of peak in the macroscopic scattering cross section of PGG-Glucan by SAXS, the existence of a small amount of ordered clusters of PGG-Glucan can be deduced. The "lattice parameter" of these ordered fasces-like clusters is consistent with the radius of the individual triple-helical rods forming a microfibrillar superstructure. These results indicate that higher aggregated forms of PGG-Glucan containing up to 8 triple helices behave as ordered fasces-like clusters. We conclude that PGG-Glucan is triple-helix aggregates formed by rigid rods stacking together side by side. We propose a molecular structural model for PGG-Glucan conformations.

Histopathology of muscle flap microcirculation following prolonged ischemia.

The purpose of this study was to evaluate histological changes occurring in the microcirculation of a muscle flap following prolonged ischemia and to correlate them with the flow hemodynamics. The cremaster muscle flap model was used for direct in vivo studies of the microcirculation. In 45 rats, vascular clamps were applied to the iliac and femoral vessels following flap isolation. Flaps were subjected to various periods of ischemia, ranging from 4 to 6 hours, and 2 hr of reperfusion. In vivo observations of the microcirculation and vessel diameter measurements were taken at 1 hour intervals for an 8 hr period. With prolonged ischemia, return of circulation to the flap was delayed and no flow was observed following 6 hr of ischemia. Morphologic changes at 6 hr revealed red cell and platelet thrombi formation within the capillaries, marked dilatation of postcapillary venules, endothelial swelling in the capillaries, and microhemorrhage formation around the venules.

[Initial experience with a new type of high energy neodymium laser in correcting stenosis of the airway]. / Pierwsze doswiadczenia z zastosowaniem nowego lasera neodymowego w leczeniu zwezen dróg oddechowych.

The aim of the study was to assess the use of a new Nd:YAG laser--mediLas fibertom--in correcting malignant and benign stenoses of the airways. Eighteen patients were included in the study. In 9 these were caused by malignant tumors, in 3 by nonmalignant tumors, in 6 by post-inflammatory stenoses of the airways. Altogether 99 laser sessions were carried out. In patients with malignant diseases complete recanalization was achieved in 6 patients, in 2 partial. One patients did not benefit form the laser procedure. In patients with benign tumors complete recanalization was achieved in all of the patients. In 5 out of 6 patients the post inflammatory stenosis was corrected. Satisfactory results observed after the second, fourth and one year after the initial laser procedure encourage to use this from of therapy in cases of malignant and nonmalignant narrowing of the airways.

Structural properties of native and sonicated cinerean, a beta- (1-->3) (1-->6)-D-glucan produced by Botrytis cinerea.

Cinerean, the extracellular beta-(1-->3) (1-->6)-D-glucan of the fungus Botrytis cinerea was studied. Electron micrographs of the native polysaccharide revealed quasi-endless fibrils with an estimated diameter of ca. 1.5 nm. A particle mass of 10(9)-10(10) daltons was determined from dilute solutions by low-angle laser light scattering. Sonication of increasing duration led to fragmentation of the native polymer with an approximately exponential decrease of mass in the range of average molecular masses between 250,000 and 50,000 daltons. Shadowed by platinum, cinerean fibril fragments with a weight-average molecular mass of 172,000 +/- 3000 daltons could be characterized from electron micrographs as a distribution of rods of most probable length of 45 nm and an average length of 72 nm. Small-angle X-ray scattering confirmed the fibrillar structure of the native cinerean and the rodlike structure of sonicated cinerean. A rod diameter of 1.9 +/- 0.2 nm and a mass per unit length of 2250 +/- 490 daltons/nm were found. The latter is in agreement with the value of 1830 daltons/nm calculated from the length distribution determined from the electron micrographs. These data-especially the mass per unit length-suggest a quaternary structure for the polysaccharide. Such a structure would explain the rigidity of the rods which, in turn, is responsible for the characteristic phase separation behaviour in aqueous solutions observed by nephelometry and viscometry.

Biological accessibility of calcitonin and osteocalcin marked 125J for rats.

Biological accessibility of calcitonin and osteocalcin marked 125J for rast. In this study we estimated the biological accessibility and the degree of biological accessibility of calcitonin in relation to highly specific marker-osteocalcin after a single intraperitoneal administration. We showed mean values of biopharmaceutical parameters for the analysed hormones.

Multimedial data base and management system for self-education and testing the students' knowledge on pathomorphology.

The composition assumed our experience in creating and using multimedial data base of examination questions and management system, which is used for. This system is implemented on microcomputers compatible with IBM PC and works in network system Net Ware 3.11. The test questions exceeded 2000 until now. The packet consists of the two functionally individual programs: ASSISTANT, which is the administrator for the databases, and EXAMINATOR which is the executive program. This system enables to use text files and add images to each question, which are adjusted to display on standard graphics devices (VGA). Standard format of the notation files enables to elaborate the results in order to estimate the scale of answers and to find correlations between the results.

Effect of extensive resection of small intestine on the enterochromaffin cells of the remaining intestinal segment.

The authors discuss the problem of quantitative changes in enterochromaffin cells in the rat small intestine after its extensive resection. An increase was found in the number of these cells in the peripheral part of the intestine 4 to 8 weeks after the operation. These quantitative changes are explained by the regenerative activity in this period.

Histoenzymatic studies on the adaptation of villi of the small intestine segment left after extensive enterotomy.

After extensive resection of the small intestine in rats, histochemical reactions of selected enzymes were studied during seven weeks to one year in the remaining segment. The rise of activity of the hydrolytic, oxidative and proteolytic enzymes in enterocytes of elongated intestinal villi indicates enhanced active transport and adaptation.