Electrophysiologic analysis of the representation of the somatosensory system in the dogfish midbrain tectum

Evoked responses in the dogfish tectum opticum were studied during electrical stimulation of the spinal cord, its dorsal roots and ramus ophthalmicus of the facial nerve. Recordings were obtained from different depth as well as from different points on the tectum surface. Evoked responses could be detected mainly on the contralateral side of the tectum opticum either as slow positive (spinal cord stimulation) or negative-positive (facial stimulation) waves which were preceeded by one or two fast, probably, presynaptic deflections and followed by a very slow low-amplitude negative wave. The evoked responses possessed the properties of tectal postsynaptic responses, being somatotopically distributed on the surface and reversely represented in the inner part of the tectal lamina. Projections of different inputs were widely overlapped, but specific areas of maximal activity were presented. These findings evidence that the tectum opticum performs a double function: a primary projecting and an integrative centre.     

Cell sources, regulatory factors and gene expression in the regeneration of the crystalline lens and retina in vertebrate animals

Over the past century extensive experimental materials have been accumulated concerning cell sources of lens and retina regeneration, successive transformations of the cells, regulatory factors, and gene expression during restitution of these eye structures. The use of nuclear and cytoplasmic markers provided convincing evidence that the removed lens is restituted from the dorsal iris cells in vivo or from embryonic cells of the pigment epithelium and retina in vitro. The removed or destroyed retina is restituted as a result of transdifferentiation of the pigment epithelium cells in amphibians, fish, birds, and mammals during embryogenesis, in larvae of some anuran amphibians, and in adult newts. Cell precursors of rods are a cell source of retina regeneration in adult fish. A subpopulation of randomly distributed cells, which are a cell source of rod formation during the normal development of the eye was found in the external nuclear layer with the use of electron microscopy and nuclear and cytoplasmic markers. These cells are not only a source of regeneration of rods, but also of cones and cells of the internal nuclear layer after destruction of the corresponding retina layers. There is a peripheral growth area in the retina of vertebrates, where multi- and unipolar cells are localized, which provide for the retina growth during ontogenesis. A paradox of retina regeneration consists in that these little differentiated cells are not a source of complete restitution of the removed or destroyed retina. They make only a small contribution to its regeneration corresponding to the growth potential of cells of this eye region, while restitution of the retina proceeds only at the expense of cells of another type of differentiation. A factor controlling the differentiated state of the cell was found in the dorsal iris during studies of lens regeneration. Removal of this factor in the early stages of cell transformations leads to the initiation of lens regeneration. The factor is not specific and was identified in many cells of vertebrates, including the pigment epithelium and limb tissues, which, as is known, may be fully restituted. Studies of gene expression during lens and retina regeneration are now at the initial stage. The greatest advances were achieved on the model of transdifferentiation of the pigment epithelium cells of chick embryos into lentoids. Expression of genes MMP115 and pP344 was established in the pigment epithelium cells, which characterize the pigmented phenotype of the initial cells. Expression of the alpha-, beta-, and delta-crystallin genes was found in the lentoids, which characterize the phenotype of regenerating structures. The gene activity appears to be switched at an intermediate stage during cell dedifferentiation. Expression of the gamma-crystallin genes during lens regeneration in adult newts is initiated after completion of dedifferentiation and cell proliferation in the dorsal iris. The genes specifically expressed in the dorsal and ventral iris and in the retina rudiment have been identified by the method of gene subtraction. Expression of homeobox-containing genes from the family of PAX genes was found during lens regeneration in adult newts and retina regeneration in adult fish. The role of growth factors (FGF) as morphogenetic factors was proved, which are involved in a yet unknown way of altering the differentiation pathway of the initial cells during formation of the neuroepithelium rudiment in chick embryos, adult newts, and fish.     

Progress and prospects of tuberculosis immunology and immunogenetics

Reviews the recent progress in immunopathogenesis, immunogenetics, immunodiagnosis, immunotherapy, and immunoprophylaxis of tuberculosis. The findings of Russian scientists (primarily at the Central Research Institute of Tuberculosis, Russian Academy of Medical Sciences) are compatible to the results of medical centers abroad.     

Intensive care of myelotoxic agranulocytosis using nonselective plasmapheresis

Plasmapheresis had a marked therapeutic effect in 14 cancer patients with grave myelotoxic complications of antitumor therapy: 13 of these patients survived, felt better, isosensitization to drugs and blood preparations was eliminated, the efficacy of common detoxifying and blood-substituting therapy improved. The therapeutic effect of the procedure was obvious even in the patient who died: the anuretic stage of acute renal failure changed for the polyuretic one. Plasmapheresis caused the most pronounced shifts in the system of homeostasis maintenance. The activation of the organism's autocleansing was attended by positive laboratory and clinical shifts.     

Isolation and certain properties of mutant alkaline phosphatase of Escherichia coli

Natural and mutant alkaline phosphatases with amino acid substitutions in the processing site and N-terminal domain of the mature polypeptide chain Val for Ala(-1), Gln for Glu (+4) and simultaneously Gln for Glu (+4) and Ala for Arg (+1) have been isolated from the periplasm and cultural fluid of E. coli. It has been found that these substitutions have little effect on the dependence of the enzyme activity on pH, ionic strength and temperature but influence its isoenzymic spectrum and decrease (almost twofold) the maximal rate of the enzyme-catalyzed reaction. Extracellular enzymes display, in contrast with periplasmic ones, other catalytic properties (Vmax) and binding activity (Km). After translocation through the outer membrane all the enzymes display decreased Vmax and increased Km. These changes are especially well-pronounced in case of the mutant protein PhoA46 which contains an uncleaved signal peptide due to the impossibility of processing resulting from the substitution of Val for Ala(-1). The Vmax for this protein is decreased 20 times, while the Km is increased 4-fold. The protein also shows a higher (in comparison with other proteins) sensitivity towards proteolytic enzymes and is less resistant upon storage. The experimental data suggest that the changes in the N-end of alkaline phosphatase located at a long distance from its active center influence the enzyme function.     

Should desmoid fibromas be operated?

The 30-year experience of P.A. Herzen Moscou Cancer Research Institute in the treatment of soft tissue desmoid fibromas (DF) is summarized. A comparative study of effectiveness of surgical, combined, radiation and medicamentous methods was carried out. Frequency of recurrences after surgical treatment made up 94%, after combined treatment with preoperative radiation it decreased 3-fold (27.5%), in cases of postoperative radiation it made up 53%, and after radiation therapy--15.7%. However radiation therapy may have limitations due to necessity for irradiation of large tumour masses and usage of high-dose ionized irradiation which results in development of postradiation tissue damages. Further research brought about an original chemohormonal therapy (tamoxiphen, vinblastin, methotrexate), which provides stable recovery in 81.3% of patients. Principal positions for management of DF are formulated.     

Preoperative care and anesthesia in surgical treatment of thyrotoxicosis

Light microscopy was used to study the structure and cellular organization of the osphradial organ of the pulmonary mollusque L. stagnalis. The osphradium unites the epithelial canal and the ganglion consisting of two cell populations. On the internal surface of the V-shaped osphradial canal there are three zones of cells: secretory, villous and epithelial. The villous zone of the canal is related with sensory bipolar and multipolar neurons of the ganglion. The irritation percepted by these cells seems to be transferred through numerous zones of neuropile to large unipolar neurons of the ganglion cortical layer.