Growth hormone receptor deficiency results in blunted ghrelin feeding response, obesity, and hypolipidemia in mice

We have previously shown that growth hormone (GH) overexpression in the brain increased food intake, accompanied with increased hypothalamic agouti-related protein (AgRP) expression. Ghrelin, which stimulates both appetite and GH secretion, was injected intracerebroventricularly to GHR-/- and littermate control (+/+) mice to determine whether ghrelin's acute effects on appetite are dependent on GHR signaling. GHR-/- mice were also analyzed with respect to serum levels of lipoproteins, apolipoprotein (apo)B, leptin, glucose, and insulin as well as body composition. Central injection of ghrelin into the third dorsal ventricle increased food consumption in +/+ mice, whereas no change was observed in GHR-/- mice. After ghrelin injection, AgRP mRNA expression in the hypothalamus was higher in +/+ littermates than in GHR-/- mice, indicating a possible importance of AgRP in the GHR-mediated effect of ghrelin. Compared with controls, GHR-/- mice had increased food intake, leptin levels, and total and intra-abdominal fat mass per body weight and deceased lean mass. Moreover, serum levels of triglycerides, LDL and HDL cholesterol, and apoB, as well as glucose and insulin levels were lower in the GHR-/- mice. In summary, ghrelin's acute central action to increase food intake requires functionally intact GHR signaling. Long-term GHR deficiency in mice is associated with high plasma leptin levels, obesity, and increased food intake but a marked decrease in all lipoprotein fractions.     

VISUAL ACUITY AND ILLUMINATION IN DIFFERENT SPECTRAL REGIONS

The relation between visual acuity and illumination was measured in red and blue light, using a broken circle or C and a grating as test objects. The red light data fall on single continuous curves representing pure cone vision. The blue light data fall on two distinct curves with a transition at about 0.03 photons. Values below this intensity represent pure rod vision. Those immediately above represent the cooperative activity of rods and cones, and yield higher visual acuities than either. Pure cone vision in this intensity region is given by central fixation (C test object). All the rest of the values above this transition region represent pure cone vision. In blue light the rod data with the C lie about 1.5 log units lower on the intensity axis (cone scale) than they do in white light, while with the grating they lie about 1.0 log unit lower than in white light. Both the pure rod and cone data with the C test object are precisely described by one form of the stationary state equation. With the grating test object and a non-limiting pupil, the pure rod and cone data are described by another form of the same equation in which the curve is half as steep. The introduction of a small pupil, which limits maximum visual acuity, makes the relation between visual acuity and illumination appear steeper. Determinations of maximum visual acuities under a variety of conditions show that for the grating the pupil has to be larger, the longer the wavelength of the light, in order for the pupil not to be the limiting factor. Similar measurements with the C show that when intensity discrimination at the retina is experimentally made the limiting factor in resolution, visual acuity is improved by conditions designed to increase image contrast. However, intensity discrimination cannot be the limiting factor for the ordinary test object resolution because the conditions designed to improve image contrast do not improve maximum visual acuity, while those which reduce image contrast do not produce proportional reductions of visual acuity.     

Kinetic studies on the reaction of ethylenediaminetetraacetatochromium(III) complex with hydrogen peroxide

The rate of reaction of [Cr(III)Y]_aq (Y is EDTA anion) with hydrogen peroxide was studied in aqueous nitrate media [μ = 0.10 M (KNO₃)] at various temperatures. The general rate equation, Rate = $\text{k}{}_1\text{+}\text{k}{}_2\text{K}{}_1\text{[H}{}^{\mathrm{+}}\text{]}{}^{\mathrm{?1}}\text{1 +}\text{K}{}_1\text{[H}{}^{\mathrm{+}}\text{]}{}^{\mathrm{?1}}$ [Cr(III)Y]_aq[H₂O₂] holds over the pH range 5–9. The decomposition reaction of H₂O₂ is believed to proceed via two pathways where both the aquo and hydroxo-quinquedentate EDTA complexes are acting as the catalyst centres. Substitution-controlled mechanisms are suggested and the values of the second-order rate constants k₁ and k₂ were found to be 1.75 × 10^?2 M^?1 s^?1 and 0.174 M^?1 s^?1 at 303 K respectively, where k₂ is the rate constant for the aquo species and k₂ is that for the hydroxo complex. The respective activation enthalpies (ΔH^*₁ = 58.9 and ΔH^*₂ = 66.5 KJ mol^?1) and activation entropies (ΔS^*₁ = ?85 and ΔS^*₂ = ?40 J mol^?1 deg^?1) were calculated from a least-squares fit to the Eyring plot. The ionisation constant pK₁, was inferred from the kinetic data at 303 K to be 7.22. Beyond pH 9, the reaction is markedly retarded and ceases completely at pH ? 11. This inhibition was attributed in part to the continuous loss of the catalyst as a result of the simultaneous oxidation of Cr(III) to Cr(VI).     

Identification of novel chromosomal regions associated with airway hyperresponsiveness in recombinant congenic strains of mice

Airway responsiveness is the ability of the airways to respond to bronchoconstricting stimuli by reducing their diameter. Airway hyperresponsiveness has been associated with asthma susceptibility in both humans and murine models, and it has been shown to be a complex and heritable trait. In particular, the A/J mouse strain is known to have hyperresponsive airways, while the C57BL/6 strain is known to be relatively refractory to bronchoconstricting stimuli. We analyzed recombinant congenic strains (RCS) of mice generated from these hyper- and hyporesponsive parental strains to identify genetic loci underlying the trait of airway responsiveness in response to methacholine as assessed by whole-body plethysmography. Our screen identified 16 chromosomal regions significantly associated with airway hyperresponsiveness (genome-wide P ≤ 0.05): 8 are supported by independent and previously published reports while 8 are entirely novel. Regions that overlap with previous reports include two regions on chromosome 2, three on chromosome 6, one on chromosome 15, and two on chromosome 17. The 8 novel regions are located on chromosome 1 (92–100 cM), chromosome 5 (>73 cM), chromosome 7 (>63 cM), chromosome 8 (52–67 cM), chromosome 10 (3–7 cM and >68 cM), and chromosome 12 (25–38 cM and >52 cM). Our data identify several likely candidate genes from the 16 regions, including Ddr2, Hc, Fbn1, Flt3, Utrn, Enpp2, and Tsc.     

In vitro steroid metabolic studies in human testes II: Metabolism of cholesterol, pregnenolone, progesterone, androstenedione and testosterone by testes of an estrogen-treated man

The effect of long-term in vivo estrogen treatment on in vitro steroidogenesis by the testes of a young man was investigated. In vitro incubation of testicular tissue of this man with ³H-pregnenolone, ³H-progesterone, ³H-androstenedione and ³H-testosterone demonstrated suppression of 17-hydroxylase activity, with little or no effect of the treatment on Δ⁵-3β-hydroxysteroid oxidoreductase, 5a-reductase and aromatase. Increased 20-hydroxysteroid oxidoreductase activity was observed. Determination of intratesticular steroid concentrations led to similar conclusions.     

Unusual Protonated Structure in the Homopurine · Homopyrimidine Tract of Supercoiled and Linearized Plasmids Recognized by Chemical Probes

Abstract

Plasmid pEJ4, which is a derivative of pUC19 containing an insert with 60-bp-long · homopurine homopyrimidine tract from sea urchin P. miliaris histone gene spacer, was studied by chemical probes of the DNA structure osmium tetroxide and glyoxal. The former probe reacts with pyrimidine bases, while the latter forms a stable product only with guanine residues. These probes can thus be applied as specific probes for the homopyrimidine and homopurine strands, respectively.

At pH 6.0 the site-specific modification of the homopurine · homopyrimidine tract by both probes was observed at native superhelical density of the plasmid. In the linear plasmid under the same conditions this modification was absent; it appeared, however, at more acid pH values. In supercoiled DNA the hypersensitivity of the homopurine homopyrimidine tract to osmium tetroxide did not substantially change when pH was decreased from 6.0 to 4.0. Changes in NaCl concentration at pH 4.5 did not influence the hypersensitivity to osmium tetroxide; at pH 6.0 this hypersensitivity decreased with increasing NaCl concentration. These results thus show that the chemical probes recognize an unusual protonated structure containing unpaired bases or non-Watson-Crick base pairs. At pH 5.6 the site-specific modification occurred at or near to the middle of the homopurine · homopyrimidine tract, suggesting that a hairpin may be involved in the unusual structure under the given conditions. From the models suggested so far for the unusual structure of homopurine · homopyrimidine tracts our results fit best the protonated triplex H form suggest by V.I. Lyamichev, S.M. Mirkin and M.D. Frank-Kamenetskii, J. Biomol. Struct. Dyn. 3, 667 (1986).     

Using multiple satellite observations to quantitatively assess and model oil pollution and predict risks and consequences to shoreline from oil platforms in the Caspian Sea

This research focused on the following objectives: (1) using satellite data to characterize the spatiotemporal distribution of anthropogenic oil spills from Oil Rocks Settlement, Chilov and Pirallahi Islands (2) stochastic modeling of the oil spill risk pose to water quality and shoreline ecosystems, and (3) validating model predictions using satellite images. 165 satellite images acquired by SENTINEL-1A, LANDSAT-8, RADARSAT, ENVISAT and ERS sensors between 1996 and 2015 were used for the detection of oil spills using object-based classification and visual interpretation. Anthropogenic hotspots were observed at three oldest oil production sites with estimated oil spilling up to 1264 m³ per day and different degrees of temporal repetition of oil spills. The largest area (5639 km²) experienced 1–10 detected oil spills, while 993 km² experienced 11–20 oil spills, 775 km² experienced 21–50 oil spills, 208 km² experienced 51–100 oil spills, and 36 km² experienced 101–150 oil spills. The majority (83% or 6157 km²) of sea surface area within the combined boundary of detected oil spills (7422 km²) had a 50% or greater chance of oil spill contamination. Approximately, 6% (44 km of 751 km) of shoreline had a 50% or greater probability of contamination with land use classes sensitive to pollution.     

Linkage between the bacterial acid stress and stringent responses: the structure of the inducible lysine decarboxylase

The Escherichia coli inducible lysine decarboxylase, LdcI/CadA, together with the inner-membrane lysine-cadaverine antiporter, CadB, provide cells with protection against mild acidic conditions (pH～5). To gain a better understanding of the molecular processes underlying the acid stress response, the X-ray crystal structure of LdcI was determined. The structure revealed that the protein is an oligomer of five dimers that associate to form a decamer. Surprisingly, LdcI was found to co-crystallize with the stringent response effector molecule ppGpp, also known as the alarmone, with 10 ppGpp molecules in the decamer. ppGpp is known to mediate the stringent response, which occurs in response to nutrient deprivation. The alarmone strongly inhibited LdcI enzymatic activity. This inhibition is important for modulating the consumption of lysine in cells during acid stress under nutrient limiting conditions. Hence, our data provide direct evidence for a link between the bacterial acid stress and stringent responses.     

Synthesis and biological evaluation of novel mono- and bivalent ASGP-R-targeted drug-conjugates

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatile synthetic approach to novel mono- and multivalent drug-conjugates containing N-acetyl-2-deoxy-2-aminogalactopyranose and anticancer drug – paclitaxel (PTX). Several molecules have demonstrated high affinity towards ASGP-R and good stability under physiological conditions, significant in vitro anticancer activity comparable to PTX, as well as good internalization via ASGP-R-mediated endocytosis. Therefore, the conjugates with the highest potency can be regarded as a promising therapeutic option against HCC.