IMPRINTING EFFECTS OF THREE AMINO ACIDS (ALANINE,LYSINE AND GLYCINE) AND THEIR OLIGOPEPTIDES INTETRAHYMENA PYRIFORMIS. DATA FROM THE HORMONE AND HORMONE RECEPTOR EVOLUTION

Hormonal imprinting takes place at the first encounter of the hormone and receptor, and results in a changed binding capacity and reaction of the cell and its progeny generations. The imprinting effect of three amino acids and their oligopeptides is studied using fluorescent-labelled peptides. Glycine and lysine could provoke positive imprinting (increased binding in the progeny generations) for their own peptides, but alanine could not. Mostly positive imprinting was provoked by glycine and lysine peptides for their own peptides of different chain length. The optimal chain length provoking self-imprinting was four for glycine, two for lysine and three for alanine. Except in this case, alanine was neutral or provoked mostly negative imprinting. After reaching the optimal chain length, there is a decline in binding. Evolutionary conclusions are discussed.     

Technique-dependent variations in cerebral microvessel blood volumes and hematocrits in the rat.

To quantitate small parenchymal microvessel blood volumes in the brain, the distribution spaces of radiolabeled red blood cells (RBC) and serum albumin (RISA) were assessed in rats by different methods of tissue sampling and radioassay. Three minutes after intravenous administration of 55Fe-RBCs and/or 125I-RISA, the rats were decapitated. The brain was either immediately frozen within the skull and later removed (head-frozen group) or rapidly removed from the skull and then frozen (brain-frozen group). Radioactivity was measured either by liquid scintillation counting of tissue pieces, which contained pial plus large and small parenchymal microvessels, or by quantitative autoradiography (QAR) of tissue sections, which indicated small parenchymal microvessel blood only. In 12 of 15 areas, the RISA, RBC, and blood volumes determined by liquid scintillation counting of head-frozen tissue pieces were equal to or greater than those of brain-frozen tissue; this indicated less than or equal to 25% greater blood retention in pial and parenchymal microvessels with head freezing. At the parenchymal microvessel level (QAR assay), the distribution volumes of RBCs, RISA, and blood were similar with the two freezing techniques; hence with QAR either freezing procedure can be used to assess small parenchymal microvessel blood volumes.     

A component of fluid absorption linked to passive ion flows in the superficial pars recta

We studied salt and water absorption in isolated rabbit superficial proximal straight tubules perfused and bathed with solutions providing oppositely directed transepithelial anion gradients similar to those which might obtain in vivo. The perfusing solution contained 138.6 mM Cl- 3.8 mM HCO-3 (pH 6.6) while the bathing solution contained 113.6 mM Cl- and 25 mM HCO-3 (pH 7.4); the system was bubbled with 95% O2-5% CO2. At 37 degrees C, net volume absorption (Jv nl min-1 mm-1) was 0.32 +/- 0.03 (SEM); Ve, the transepithelial voltage (millivolts; lumen to bath), was +3.1 +/- 0.2. At 21 degrees C, Ve rose to +3.7 +/- 0.1 and Jv fell to 0.13 +/- 0.01 (significantly different from zero at P less than 0.001); in the presence of 10(-4)M ouabain at 37 degrees C, Ve rose to +3.8 +/- 0.1 and Jv fell to 0.16 +/- 0.01 (P less than 0.001 with respect to zero). In paired experiments, the ouabain- and temperature-insensitive moieties of Jv and Ve became zero when transepithelial anion concentration gradients were abolished. Titrametric determinations net chloride flux at 21 degrees C or at 37 degrees C with 10(-4) M ouabain showed that chloride was the sole anion in an isotonic absorbate. And, combined electrical and tracer flux data indicated that the tubular epithelium was approximately 18 times more permeable to Cl- than to HCO-3. We interpret these results to indicate that, in these tubules, NaCl absorption depends in part on transepithelial anion concentration gradients similar to those generated in vivo and in vitro by active Na+ absorption associated with absorption to anions other than chloride. A quantitative analysis of passive solute and solvent flows in lateral intercellular spaces indicated that fluid absorption occurred across junctional complexes when the osmolality of the lateral intercellular spaces was equal to or slightly less than that of the perfusing and bathing solutions; the driving force for volume flow under these conditions depended on the fact that sigmaHCO3 exceeded sigmaCl.     

Intense photon emission induced by fracture of γ–irradiated Dy‐, Tm‐, Sm‐ and Mn‐doped CaSO4 single crystals

When an γ‐irradiated Dy‐, Tm‐, Sm‐ or Mn‐doped CaSO₄ crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post‐deformation region of the crystals. In this study, intensities I_m1 and I_m2 corresponding to first and second ML peaks, respectively, increased linearly with an impact velocity v₀ of the piston used to deform the crystals, and times t_m1 and t_m2 corresponding to the first and second ML peaks, respectively, decreased with impact velocity. Total ML intensity initially increased with impact velocity and then reached a saturation value for higher values of impact velocity. ML intensity increased with increasing γ‐doses and size of crystals. Results showed that the electric field produced as a result of charging of newly‐created surfaces caused tunneling of electrons to the valence band of the hole‐trapping centres. The free holes generated moved in the valence band and their subsequent recombination with electron trapping centres released energy, thereby resulting in excitation of luminescent centres. Copyright © 2012 John Wiley & Sons, Ltd.     

Cell Budding from Normal Appearing Epithelia: A Predictor of Colorectal Cancer Metastasis?

Background: Colorectal carcinogenesis is believed to be a multi-stage process that originates with a localized adenoma, which linearly progresses to an intra-mucosal carcinoma, to an invasive lesion, and finally to metastatic cancer. This progression model is supported by tissue culture and animal model studies, but it is difficult to reconcile with several well-established observations, principally among these are that up to 25% of early stage (Stage I/II), node-negative colorectal cancer (CRC) develop distant metastasis, and that circulating CRC cells are undetectable in peripheral blood samples of up to 50% of patients with confirmed metastasis, but more than 30% of patients with no detectable metastasis exhibit such cells. The mechanism responsible for this diverse behavior is unknown, and there are no effective means to identify patients with pending, or who are at high risk for, developing metastatic CRC.Novel findings: Our previous studies of human breast and prostate cancer have shown that cancer invasion arises from the convergence of a tissue injury, the innate immune response to that injury, and the presence of tumor stem cells within tumor capsules at the site of the injury. Focal degeneration of a capsule due to age or disease attracts lymphocyte infiltration that degrades the degenerating capsules resulting in the formation of a focal disruption in the capsule, which selectively favors proliferating or “budding” of the underlying tumor stem cells. Our recent studies suggest that lymphocyte infiltration also triggers metastasis by disrupting the intercellular junctions and surface adhesion molecules within the proliferating cell buds causing their dissociation. Then, lymphocytes and tumor cells are conjoined through membrane fusion to form tumor-lymphocyte chimeras (TLCs) that allows the tumor stem cell to avail itself of the lymphocyte''s natural ability to migrate and breach cell barriers in order to intravasate and to travel to distant organs. Our most recent studies of human CRC have detected nearly identical focal capsule disruptions, lymphocyte infiltration, budding cells, and the formation of TLCs. Our studies have further shown that age- and type-matched node-positive and -negative CRC have a significantly different morphological and immunohistochemical profile and that the majority of lymphatic ducts with disseminated cells are located within the mucosa adjacent to morphologically normal appearing epithelial structures that express a stem cell-related marker.New hypothesis: Based on these findings and the growth patterns of budding cells revealed by double immunohistochemistry, we further hypothesize that metastatic spread is an early event of carcinogenesis and that budding cells overlying focal capsule disruptions represent invasion- and metastasis-initiating cells that follow one of four pathways to progress: (1) to undergo extensive in situ proliferation leading to the formation of tumor nests that subsequently invade the submucosa, (2) to migrate with associated lymphocytes functioning as “seeds” to grow in new sites, (3) to migrate and intravasate into pre-existing vascular structures by forming TLCs, or (4) to intravasate into vascular structures that are generated by the budding cells themselves. We also propose that only node-positive cases harbor stem cells with the potential for multi-lineage differentiation and unique surface markers that permit intravasation.     

A mutant heterodimeric myosin with one inactive head generates maximal displacement

Each of the heads of the motor protein myosin II is capable of supporting motion. A previous report showed that double-headed myosin generates twice the displacement of single-headed myosin (Tyska, M.J., D.E. Dupuis, W.H. Guilford, J.B. Patlak, G.S. Waller, K.M. Trybus, D.M. Warshaw, and S. Lowey. 1999. Proc. Natl. Acad. Sci. USA. 96:4402-4407). To determine the role of the second head, we expressed a smooth muscle heterodimeric heavy meromyosin (HMM) with one wild-type head, and the other locked in a weak actin-binding state by introducing a point mutation in switch II (E470A). Homodimeric E470A HMM did not support in vitro motility, and only slowly hydrolyzed MgATP. Optical trap measurements revealed that the heterodimer generated unitary displacements of 10.4 nm, strikingly similar to wild-type HMM (10.2 nm) and approximately twice that of single-headed subfragment-1 (4.4 nm). These data show that a double-headed molecule can achieve a working stroke of approximately 10 nm with only one active head and an inactive weak-binding partner. We propose that the second head optimizes the orientation and/or stabilizes the structure of the motion-generating head, thereby resulting in maximum displacement.     

Effects of postnatal dexamethasone on blood-brain barrier permeability and brain water content in newborn lambs

We showed that antenatal corticosteroids reduced blood-brain barrier permeability in fetuses at 60 and 80%, but not 90% of gestation, and decreased brain water content in fetuses. Our objective was to examine the effects of postnatal corticosteroids on regional blood-brain barrier permeability and brain water content in newborn lambs. Three dexamethasone treatment groups were studied in 3- to 5-day-old lambs. A 0.01 mg/kg dose was selected to estimate the amount of dexamethasone that might have reached fetuses via antenatal treatment of ewes in our previous studies. The other doses (0.25 and 0.5 mg/kg) were chosen to approximate those used clinically to treat infants with bronchopulmonary dysplasia. Lambs were randomly assigned to receive four intramuscular injections of dexamethasone or placebo given 12 h apart on days 3 and 4 of age. Blood-brain barrier function was measured with the blood-to-brain transfer constant (K(i)) to alpha-aminoisobutyric acid, brain plasma volume was measured with polyethylene glycol for the calculation of K(i,) and brain water was measured by wet-to-dry tissue weights. Postnatal treatment with corticosteroids did not reduce barrier permeability in newborn lambs. Brain blood volume was higher in the 0.25 and 0.5 mg/kg dose dexamethasone groups than in the placebo group. Brain water content did not differ among the groups. We conclude that postnatal treatment with corticosteroids did not reduce regional blood-brain barrier permeability or brain water content but increased the brain plasma volume in newborn lambs. These findings are consistent with our previous work indicating that barrier permeability is responsive to corticosteroids at 60 and 80% of gestation and brain water regulation at 60% of gestation, but not in near-term fetuses or newborn lambs.     

The correlation of protein structure and evolution of a protein-coding gene: phylogenetic inference using cytochrome oxidase III

Discriminating phylogenetic signal from noise in DNA sequence data is a difficult problem in phylogenetic inference at higher systematic levels. For protein-coding genes, noise at synonymous (silent) positions can be filtered by deleting entire codon positions or types of change at a codon position. This method is not appropriate for replacement sites, because changes at each site within a codon may not be independent. This research presents a method using information from protein structure to evaluate variation in replacement sites. Analysis of the correlation of amino acid variation with protein structure identified rapidly evolving codons in the COIII gene. In a series of phylogenetic analyses attempting to recover a known set of vertebrate relationships, downweighting these labile codons produced the most accurate results. Structural correlates of variable and invariant residues identified in this study can be used to increase the accuracy of models used for phylogenetic inference. Viewing amino acid variation within a phylogenetic framework provided insight into residue changes important in the secondary and tertiary structures of the molecule, changes that were correlated between pairs of neighboring residues or between residues in neighboring helices.      

Ultrasound imaging in an experimental model of fatty liver disease and cirrhosis in rats

Background

Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.

Results

This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.

Conclusions

Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage.