Pathway across blood-brain barrier opened by the bradykinin agonist, RMP-7.

The route taken by lanthanum (MW 139) across cerebral endothelium was delineated when the blood-brain barrier was opened by RMP-7, a novel bradykinin agonist. Balb C mice were infused through a jugular vein with LaCl3 with or without RMP-7 (5 micrograms/kg). Ten minutes later, the brains were fixed with aldehydes and processed for electron microscopy. The patency of the junctions between endothelial cells was estimated by counting the number of junctions penetrated by LaCl3. Tracer penetrated the junctions in about 25% of microvessels in vehicle infused, control mice and about 58% in the RMP-7 group, where more junctions per vessel were also penetrated. The LaCl3 then penetrated the basal lamina in about 20% of all microvessels in the RMP-7 group, versus 0.50% in the control group. From the basal lamina, the tracer entered perivascular spaces in about 13% of all microvessels in the RMP-7 group and about 0.07% in the controls. Very few endocytic pits or vesicles in the RMP-7 group were labeled, so LaCl3 did not cross endothelium by transcytosis. The increased number of tight junctions penetrated by tracer and its spread into periendothelial basal lamina and interstitial clefts indicated, therefore, a paracellular route of exudation in the RMP-7 treated animals.

Developmental changes in the ultrastructure of the lamprey lateral line nerve during metamorphosis.

The ultrastructure of the trunk lateral line nerve of larval and adult lampreys was studied with transmission electron microscopy. We confirmed that lampreys' lateral line nerve lacks myelin. Nevertheless, all axons were wrapped by Schwann cell processes. In the larval nerve, gaps between Schwann cells were observed, where the axolemma was covered only by a basal lamina, indicating an earlier developmental stage. In the adult nerve, glial (Schwann cell) ensheathment was mostly complete. Additionally, we observed variable ratios of axons to Schwann cells in larval and adult preparations. In the larval nerve, smaller axons were wrapped by one Schwann cell. Occasionally, a single Schwann cell surrounded two axons. Larger axons were associated with two to five Schwann cells. In the adult nerve, smaller axons were surrounded by one, but larger axons by three to eight Schwann cells. The larval epineurium contained large adipose cells, separated from each other by single fibroblast processes. This layer of adipose tissue was reduced in adult preparation. The larval perineurium was thin, and the fibroblasts, containing large amounts of glycogen granules, were arranged loosely. The adult perineurium was thicker, consisting of at least three layers of fibroblasts separated by collagen fibrils. The larval and adult endoneurium contained collagen fibrils oriented orthogonally to each other. Both larval and adult lateral line nerves possessed a number of putative fascicles weakly defined by a thin layer of perineurial fibroblasts. These results indicate that after a prolonged larval stage, the lamprey lateral line nerve is subjected to additional maturation processes during metamorphosis.

Metamorphosis-related changes in the lateral line system of lampreys, Petromyzon marinus.

Lamprey metamorphosis leads to considerable changes in morphology and behavior. We have recently reported that larval lampreys possess a functional lateral line system. Here we investigated metamorphic morphological changes in the lateral line system using light and electron microscopy. Functional modifications were studied by recording the trunk lateral line nerve activity of larvae and adults while stimulating neuromasts with approximately sinusoidal water motion. We found a general re-patterning of neuromasts on the head and trunk including an increase in numbers, redistribution within the pit lines, and shifts of the pit lines relative to external features. The trunk lateral line nerve response was qualitatively similar in adults and larvae. Both showed two neuronal populations responding to opposite directions of water flow. Magnitude of the response increased monotonically with stimulus amplitude. At low frequencies, the response lag relative to the stimulus maximum was approximately 220 degrees , and the gain depended approximately linearly on frequency, confirming that superficial neuromasts are velocity detectors. Changes in phase lag with increasing stimulus frequency were steeper in larvae, suggesting slower afferent conductance. The response gain with frequency was smaller for adults, suggesting a narrower frequency discrimination range and decreased sensitivity. These changes may be adaptations for the active lifestyle of adult lampreys.

[Correlation of the destructive and reparative processes in neurons of the cerebral cortex in rats after thermal injury]. / O sootnoshenii destruktivnykh i reparativnykh protsessov v neironakh kory bol'shikh polusharii golovnogo mozga krys pri termicheskoi travme.

Rat brain sensorimotor cortical neurons were investigated in thermal trauma, using electron microscopic radioautography. RNA synthesis and destructive neuronal changes (chromatolysis, nuclear and mitochondrial damage) have been determined. It has been established that the development of a reparative process--ribosomal RNA synthesis--was roughly parallel to the appearance of destructive changes and was marked in neurons with considerable ultrastructural disturbances.

[Electron microscopic and radioautographic data on the synthesis of RNA and chromatin structure in cells of the rat cerebral cortex]. / Elektronno-radioavtograficheskie dannye o sinteze RNK i stroenii khromatina v kletkakh kory bol'shikh polusharii golovnogo mozga krys.

The intensity of RNA synthesis in cells of the rat brain hemispheres (neurons, astrocytes, oligodendrogliocytes, microgliocytes) was studied by electron microscopic radioautography, and the data obtained were compared with dispersed to condensed chromatin area ratio. The correlation was found between the level of RNA synthesis and dispersed chromatin area. High chromatin dispersity in neuron and intensive NA synthesis in the extranucleolar part of the nucleus made it possible to assume the existence of depression of an especially large genome part and the variability of the proteins produced by this cell.

[Limits of several cell nucleus reactions in old age and in the presence of a pathological process]. / O predele nekotorykh reaktsii iadra kletki v starosti i pri khronicheskom patologicheskom protsesse.

The number of nucleoli and the structure of nucleolus-associated chromatin (determined by the number of perinucleolar chromocentres) was investigated in two groups of mice. The first group was control, and the second one--experimental, given CCl4 injections once a week, for one year. A gradual increase of the number of nucleoli and chromocentres bound with nucleoli was revealed with ageing in control mice. In the experimental group both indices quickly reached the maximum which was equal or even higher than in old control mice. The subsequent development of the pathological process failed to alter these indices. Possible mechanisms limiting the range of the mentioned changes of the nuclei are discussed.

[RNA synthesis in cells of the cerebral cortex of mice according to electron-microscopic autoradiography findings]. / Sintez RNK v kletkakh kory golovnogo mozga u myshei po dannym élektronno-mikroskopicheskoi avtoradiografii

An electron microscopy autoratiographic study of the RNA synthesis in the neurons of the mouse cerebral cortex revealed the highest label concentration in the nucleoli. A considerable amount of silver grains was concentrated over the nucleoplasm. The content of the radioactive substance in the cytoplasm of the neurons 2 1/2 hours after the animal was injected with 3H-5-uridine was lower than in the other kinds of cells at the same period of their contact with the labeled precursor. A considerable difference in the amount of silver grains was observed over the serial sections of the same nucleolus and in the way of the label distribution in the neurons located nearby.

[Characteristics of RNA production in the body of the nucleolus studied by an analysis of serial electron microscopic radioautographs]. / Izuchenie osobennostei produktsii RNK v tele iadryshka putem analiza seriinykh élektronno-mikroskopicheskikh radioavtografov.

Electron microscopic radioautography was used to examine the changes in the density of silver grains over the serial sections of neurons of the fifth layer of the rat cortex after injection of 3H-uridine. In the majority of the neurons under study, the changes in the density of silver grains over the sections of nucleoli did not correlate with those in the density over the sections of the extranucleolar part of the nucleus. On the basis of these findings the conclusion is drawn that essential differences in the grain density in the neighbouring sections of the nucleolus are caused by non-uniformity of distribution of newly synthesized RNA in the nucleolus rather than by the errors of the method described. Possible reasons for such a non-uniformity are discussed.

[Electron autoradiographic study of RNA synthesis in cerebral cortex neurons in burns]. / Elektronno-avtoradiograficheskoe issledovanie sinteza RNK v nevronakh kory bol'shikh polusharii golovnogo mozge krys pri termicheskoi travme.

RNA synthesis in neuronal nucleoli of the rat cerebral cortex was studied by electron microscopic autoradiography in rats before and 1, 12 h, 3 and 6 days after burn injury. It was ascertained that the rate of RNA synthesis begins increasing rapidly after burn injury (1 h) and reaches high level after 12 h. The decrease in the rate of RNA synthesis proceeds more slowly than the increase. This rate does not return to normal even by the close of day 6 following injury.

[Electron autoradiographic study of the distribution of 3H-adrenaline in the central nervous system]. / Elektronno-avtoradiograficheskoe issledovanie raspredeleniia adrenalina-3H v tsentral'noi nervnoi sisteme.

3H-Adrenaline was injected into the rat lateral brain ventricle. Half an hour after injection the brain tissue was fixed and the distribution pattern of labeled adrenaline was studied by electron microscopic autoradiography. Silver granules were located mainly above the neuropile. The label content was infrequently different in adjacent synapses. Reasons for dissimilar labeling of adjacent synapses and possibility of using labeled exogenous mediators for studying function of the central nervous system are discussed.

[Immunomorphologic and ultrastructural features of the thymus in myasthenia]. / Immunomorfologicheskie i ul'trastrukturnye osobennosti vilochkovoi zhelezy pri miastenii.

Morphologic, ultrastructural changes in the epithelial component of the thymus in 41 patients with myasthenia are analyzed. Studies by histochemical, ultrastructural, and immunofluorescent methods revealed that the severity of the clinical course of myasthenia was related to the degree of changes in the epithelial component of the thymus, in its specific structures, Hassal's bodies. Effect of thymic epithelial component on lymphoid immunogenesis-regulating component was detected.

[Method of electron-autoradiographic study of nucleic acid biosynthesis in bacteria during phagocytosis]. / Metodika élektronno-avtoradiograficheskogo issledovaniia sinteza nukleinovykh kislot v bakteriiakh pri fagotsitoze.

Leukocytes from healthy men exposed to Staphylococcus epidermis were incubated with 3H-uridine and 3H-thymidine. The level of nucleic acid synthesis by phagocyted bacteria was examined by electron microscopic autoradiography. The method makes it possible to correlate bacterial and phagocyte functions with their ultrastructures.