New observations and reinterpretation on the enigmatic taxon Colombitherium (?Pyrotheria,Mammalia) from Colombia

Abstract: The controversial taxon Colombitherium tolimense (Mammalia) (probably Late Eocene in age) from Colombia, although known for nearly 40 years, still bears much mystery. Aside from the problematic ordinal attribution of the holotype and only specimen, its determination as an upper or lower jaw remains a highly debated issue. New observations include the presence of a contact facet on the distal face of the most posterior tooth, which indicates that the fragmentary jaw preserves three premolars and two molars; the M3, unpreserved but present, being most probably reduced. This new interpretation completely fits the morphology of the teeth. Furthermore, the shape of these latter and the deeper wear encompassed by their lingual part relative to the labial one is typical of upper dentition. This is in agreement with the internal curving of the roots of the anterior premolars and with several other arguments that lead interpreting the holotype of C. tolimense as a maxillary bearing P2‐M2. This new interpretation deepens the morphological gap between Colombitherium and other pyrotherians (except Proticia) and challenges further its referral to Pyrotheria. The peculiar morphology of Colombitherium relative to other pyrotherians is indeed striking. In fact, Colombitherium has nothing in common with pyrotherians but bilophodont cheek teeth, a feature largely widespread in placental mammals. It is here referred to ?Pyrotheria until additional evidence of its relationships is known. Associated with the putative removal of Proticia from Pyrotheria as argued by some authors, the hypothetical removal of Colombitherium from the order would adjust the widely accepted assumption that the pyrotherian bilophodont cheek teeth originated from bunodont cheek teeth. It would also make an origin from lophodont forms plausible. This in turn would have critical relevance, especially to the hypothesis that pyrotherians are notoungulates.     

Surface of the vascular plexuses of human cerebral ventricles

The racemose part of vascular plexuses of the lateral ventricles has been studied in fetuses and persons at various age in the scanning and transmissive electron microscopes. In the magistral arteries of the vascular plexuses the neural trunks have been studied. They form the periadventitial plexus with a more complex network of connections in mature persons. The sulci and the elongated folds between them make the relief of the plexus. A rough surface of epitheliocytes has deep craters and irregular protrusions, microvilli, cilia and spherical bodies. The epitheliocytes are arranged in a single layer and connected with each other by means of protoplasmic peduncles. Over the epithelial layer, as single groups, Kolmer cells are situated.     

Changes in the secondary structure bacteriophage T4 envelope protein after its polymerization

Circular dichroism (CD) spectra of the structural protein of the bacteriophage T4 sheath (gp 18) in a monomeric native state, helices, polysheaths and contracted sheaths were measured in the range 184-310 nm. The secondary structure of the protein studied was calculated from the spectra in the range 190-240 nm according to Provencher and Gl?ckner. It has been shown that the polymerization is proceeded without change of the alpha-helical content in the secondary structure of gp 18: estimated alpha-helix in monomeric gp 18, helices and polysheaths was 39%. The beta-form content in monomeric gp 18, helices and polysheaths was 33, 32 and 37%, respectively. Tail sheath contraction is attended by a 14% decrease in gp 18 alpha-helicity and a 5% increase in its beta-form content.     

Changes in the peripheral blood, liver and spleen during the long-term experimental administration of modified hemoglobin

The study of chronic toxicity of polymerized hemoglobin solutions (PHb) has demonstrated the relationship between the dose of the solution administered and the level of functional and morphological changes induced in various organs of experimental animals. Lower doses (1.8 g/kg) of PHb had no effect on the values of protein and carbohydrate metabolism, while the high doses (10-15 g/kg) of PHb resulted in the impairment of protein synthesis, morphological changes in the spleen and lymphatic nodes.     

Isolation and purification of Mn-peroxidase from Azospirillum brasilense Sp245

Homogenous Mn-peroxidase of a 26-fold purity grade was isolated from a culture of Azospirillum brasilense Sp245 cultivated on a medium containing 0.1 mM pyrocatechol. The molecular weight of the enzyme is 43 kD as revealed by electrophoresis in SDS-PAAG. It was shown that the use of pyrocatechol and 2,2'-azino-bis(3-ethylbenzotiazoline-6-sulfonate) at concentrations of 0.1 and I mM as inductors increased the Mn-peroxidase activity by a factor of 3.     

Micellar peroxidase-catalyzed synthesis of chiral polyaniline

Micellar peroxidase-catalyzed synthesis of chiral polyaniline (PANI) in the presence of dodecylbenzenesulfonic acid (DBSA) was developed. The effect of DBSA concentration on the catalytic efficiency of horseradish and palm tree peroxidases was examined. Favorable conditions for the enzymatic synthesis of chiral PANI, determined by a multiple factors design, demonstrated that the PANIs with the highest chirality were produced in the presence of low concentrations of optically active camphorsulphonic acid (CSA). Unexpectedly, the chiral PANI was also synthesized in the absence of CSA in feed. The favorable conditions for the enzymatic production of chiral and conducting PANIs were shown to be different. The morphology of the chiral PANI particles was examined by transmission and scanning electron microscopies.     

Structure and regulation of the assembly of bacteriophage T4 fibrillar proteins. I. Isolation and spectral properties of long fibers

A preparative procedure for purification of the biological active proximal (A) and distal (BC') parts of bacteriophage T4 long-tail fibers is described. Absorption spectra of these proteins in the near ultraviolet region were measured. The absorption coefficients were determined on the basis of the nitrogen content, the absorption coefficient for the A part is epsilon 0.1% 277 nm = 0.93 +/- 0.06 and for the BC' part is epsilon 0.1%, 277,5 nm = 1.01 +/- 0.08. Calculations of the secondary structure from CD spectra show that there is a high content of beta-structure: 41% in the A part and 51% in the BC' part,--and also that alpha-helix are present in the native complex: 20% in A and 7% in BC'. A model for the spatial organisation of long fibers is proposed.     

Investigation of enzymatic degradation of pectin polysaccharides under limiting conditions

The dynamics of changes in spectra of oligosaccharide fragments formed during enzymatic degradation of plant pectins at low enzyme/substrate ratio was studied. It is shown that degradation of deesterified pectin molecules is a discrete and determined process manifested in establishment of a stable polysaccharide spectrum. It is noted that introduction of chemical modifications into the polysaccharide substrate structure preserves the discreteness of the polymer molecule fragmentation but changes the spectrum of formed oligosaccharide fragments. It is supposed that degradation is defined by the spatial (three-dimensional) organization of the polysaccharide molecule.     

Synthesis and study of B-nor-8-isoanalogs of steroid estrogens

The study of the binding of estradiol B-nor-8-isonalogues to estrogen receptors from the rat uterus helped create the proposed model of the corresponding ligand-receptor complexes. The use of this model ensured the choice of such micromodifications in this steroid group that sharply decreased their hormonal activity. By the example of 16,16-dimethyl-D-homo-B-nor-8-isoestrone, we demonstrated the possibility of the synthesis of the estrogen analogues devoid of uterotropic activity but retaining immunosuppressive activity.     

Radiologic follow-up and prognosis of efficiency of systemic Sr-89 Cl-2 therapy of bone metastases in prostate cancer

We evaluated possibilities of bone scintigraphy with 99mTc-methylendiphosphonate (99mTc-MDP) and magnetic resonance imaging (MRI) in follow-up and prediction of effect in patients with extensive bone metastatic disease treated with betha-emitter 89SrCl2. 24 patients with prostate cancer and extensive metastatic involvement of skeleton were referred for the study. 89SrCl2 was injected as single injection of 150 MBq (4 mCi), in eighteen from Amersham plc., England, as Metastron, in six--from Medradiopreparat, Russia). In all patients bone scintigraphy with 99mTc-MDP and MRI study of metastatic regions were performed before and in 3 months after 89SrCl2 injection. Patients treated with Metsatron were also studied in 6 months after injection. Quantitative analysis of data comprised count and anatomic dimensions of metastatic areas and calculation of indices [metastasis/intact bone] both for scintillation count of 99mTc-MDP bone scans and signal intensity of T1-weighted MRI scan. Henceforth, we conclude the data of bone scanning with 99mTc-MDP and of MRI give evidencies for significant regress of bone metastases in patients treated with 89SrCl2 besides symptomatic suppression of pain syndrome. 99mTc-MDP bone scanning is also of predictive value for the prognosis of therapeutic effect of systemic radiotherapy with 89SrCl2 in prostate cancer.