Obesity and insulin resistance in human growth hormone transgenic rats

A line of transgenic rats (heterozygotes) carrying a chimeric gene comprising a regulatory portion of murine whey acidic protein and a structural portion of human GH (hGH) genes developed severe obesity with age. To characterize physiological mechanisms that lead to fat accumulation, an array of parameters related to obesity were studied. Blood hGH levels were continuously low, endogenous rat GH secretion was suppressed, and the pulsatility in peripheral GH levels was absent. Plasma glucose, insulin, triglyceride, and FFA levels in the male transgenic rats significantly exceeded those in nontransgenic littermates at 12 and 17 weeks, but not at 7 weeks, of age. All symptoms except hyperlipidemia were restored to normal by treatment with an antidiabetic agent, thiazolidinedione (troglitazone), for 1 week from 17 weeks of age. As phenotypic expression of obesity was already evident before aberration of physiological parameters, it was assumed that animals had a condition in which obesity or hyperlipidemia caused hyperinsulinemia. Gene expression and enzymatic activity of lipoprotein lipase in the adipose tissue in the transgenic rats were not different from those in normal rats. In contrast, the gene expression level of glycerol-3-phosphodehydrogenase was markedly elevated, suggesting that glycerol synthesis was much enhanced in the adipocytes of the transgenic rats. In an i.p. glucose tolerance test, the transgenic rats were not hyperglycemic at 7 weeks of age; however, the animal became hyperglycemic at 15-17 weeks of age. Finally, treatment with recombinant hGH for 1 week to produce pulsatile secretion reduced the size of epididymal and kidney fat pads and restored normal weight gain. These observations suggest that continuously low peripheral GH levels with the lack of pulsatile secretion resulted in obesity and noninsulin-dependent diabetes mellitus.     

Dielectric study of β-relaxation in some cellulosic substances

6-(2-Cyanoethylamino)-6-deoxycellulose (Cell-CEA) as a novel cellulose derivative was prepared from 6-bromo-6-deoxycellulose. The influence of the reaction conditions on the degree of substitution was studied in detail. The dielectric characteristics of a Cell-CEA sample having degree of substitution of 0.86, together with those of microcrystalline and regenerated celluloses, have been investigated in the temperature range from −60 to 120°C, and frequency range 30 Hz to 100kHz. One relaxation process, designated as β, was recognised, which was attributed to side-group motions, probably −CH₂X (X = OH or NHCH₂CH₂CN). The higher activation energy of this process and the shift to higher temperature in Cell-CEA, compared with microcrystalline and regenerated celluloses, reflects the enhanced steric constraints involved in the motion of the bulkier, −CH₂NHCH₂CH₂CN, side groups. The results obtained are discussed in terms of the dielectric parameters ϵ″_max′ β and Δϵ.     

Sorption and permeation of iodine in water-swollen poly(vinyl alcohol) membranes and iodine complex formation

The sorption and the permeation of iodine in water-swollen poly(vinyl alcohol) (PVA) membranes and the formation of PVA–iodine complexes were studied. The logarithms of the permeability and the diffusion coefficient decreased approximately linearly with the increase in polymer volume fraction. When the membrane was soaked in an aqueous I₂–KI solution, it contracted and Young's modulus increased. These findings were explained in terms of the formation of extra junction points due to the PVA–iodine complexes. These changes were reversible and could be recovered by replacing the solution with water. The length of the polyiodine chain increased with the increase in the degree of hydration of the membrane. At a fixed degree of hydration, Young's modulus of an iodine-sorbed membrane was much greater than that of a membrane soaked in pure water. This finding was explained on the basis of a double-network structure. The extension of the membrane promoted the complex formation, and the complex disappeared when the tension was released. The critical strain necessary for the complex formation was independent of the degree of hydration. The length of polyiodine chain increased with strain and became constant at higher strains.     

Formation of acrolein-derived 2'-deoxyadenosine adduct in an iron-induced carcinogenesis model

Acrolein is a representative carcinogenic aldehyde found ubiquitously in the environment and formed endogenously through oxidation reactions, such as lipid peroxidation and myeloperoxidase-catalyzed amino acid oxidation. It shows facile reactivity toward DNA to form an exocyclic DNA adduct. To verify the formation of acrolein-derived DNA adduct under oxidative stress in vivo, we raised a novel monoclonal antibody (mAb21) against the acrolein-modified DNA and found that the antibody most significantly recognized an acrolein-modified 2' -deoxyadenosine. On the basis of chemical and spectroscopic evidence, the major antigenic product of mAb21 was the 1,N6-propano-2' -deoxyadenosine adduct. The exposure of rat liver epithelial RL34 cells to acrolein resulted in a significant accumulation of the acrolein-2' -deoxyadenosine adduct in the nuclei. Formation of this adduct under oxidative stress in vivo was immunohistochemically examined in rats exposed to ferric nitrilotriacetate, a carcinogenic iron chelate that specifically induces oxidative stress in the kidneys of rodents. It was observed that the acrolein-2' -deoxyadenosine adduct was formed in the nuclei of the proximal tubular cells, the target cells of this carcinogenesis model. The same cells were stained with a monoclonal antibody 5F6 that recognizes an acrolein-lysine adduct, by which cytosolic accumulation of acrolein-modified proteins appeared. Similar results were also obtained from myeloperoxidase knockout mice exposed to the iron complex, suggesting that the myeloperoxidase-catalyzed oxidation system might not be essential for the generation of acrolein in this experimental animal carcinogenesis model. The data obtained in this study suggest that the formation of a carcinogenic aldehyde through lipid peroxidation may be causally involved in the pathophysiological effects associated with oxidative stress.     

Transcutaneous Blood Flow Measurement by Electromagnetic Induction

A new induction flowmeter which can measure the blood flow from the skin surface is discussed theoretically and experimentally. A pair of electrodes placed on the skin detect the EMF induced by the interaction of the blood flow and a magnetic field applied from outside the skin. The relation between the EMF and the flow rate, which is obtained theoretically, is also confirmed experimentally within the error of 10 percent.     

Effect of Substituents on Dielectric β-Relaxation in Cellulose

The dielectric characteristics for some cellulose derivatives, namely chlorodeoxycellulose (Cell-Cl; degree of substitution of chlorine, DS_Cl=0·87), bromodeoxycellulose (Cell-Br; DS_Br=0·92) and thiocyanatodeoxycellulose (Cell-SCN; DS_SCN=0·88), all substituted only at C-6, together with those of regenerated cellulose, have been investigated in the temperature range -60 to 120°C, and in the frequency range 0·2–100kHz. Only one relaxation process, designated as β, was identified within the frequency and temperature ranges studied. The activation energy of this relaxation increases in the order Cell-Cl<Cell-Br<Cell-SCN, suggesting that the bulkiness of the substituent was the determining factor of the activation energy. The characteristic dielectric parameters, namely polarization magnitude (Δε) and shape parameter (α or β-), were obtained by the analysis of absorption bands and are discussed in relation to the substituent effect. © of SCI.     

Linear Phase Emphasis Networks with Gaussian Function

In this paper, a new approach to the practical design and realization methods of linear phase emphasis network, which is applicable to the FM transmission system, is introduced. The methods are based on employing the Gaussian function expressed as a real exponential function exp(P2) realized by the squared amplitude response of a specific two-port passive LC ladder network. They are also based on a time base conversion technique using digital technology which provides a zero phase network.     

The effect of syndiotacticity of the structure and properties of dehydrochlorinated poly(vinyl chloride) films

The dehydrochlorination of a syndiotacticity-enriched poly(vinyl chloride) (s-PVC) gave polyene materials and the structure and properties of dehydrochlorinated specimens were studied. The results were compared with those obtained for polyene materials formed from a commercial poly(vinyl chloride) (c-PVC). The crystallinity of the s-PVC was higher than that of the c-PVC as revealed by the infrared analysis and X-ray diffraction studies. The dehydrochlorinated specimens from the s-PVC were crystalline to some extent while those from the c-PVC were amorphous. The molecular orientation in the original films was preserved in the dehydrochlorinated specimens. The polyene films from the s-PVC had larger conductivities and showed better doping properties as compared with those from the c-PVC. These results were explained in terms of the larger crystallinity and the increased structural regularity of the s-PVC as compared with those of the c-PVC.     

Chemical-Labeling-Assisted Detection of Nucleobase Modifications by Quantum-Tunneling-Based Single-Molecule Sensing

Quantum-tunneling-based DNA sensing is a single-molecule technique that promises direct mapping of nucleobase modifications. However, its applicability is seriously limited because of the small difference in conductivity between modified and unmodified nucleobases. Herein, a chemical labeling strategy is presented that facilitates the detection of modified nucleotides by quantum tunneling. We used 5-Formyl-2′-deoxyuridine as a model compound and demonstrated that chemical labeling dramatically alters its molecular conductance compared with that of canonical nucleotides; thus, facilitating statistical discrimination, which is impeded in the unlabeled state. This work introduces a chemical strategy that overcomes the intrinsic difficulty in quantum-tunneling-based modification analysis—the similarity of the molecular conductance of the nucleobases of interest.     

Effect of magnetic field strength and admixture gas on current interrupting capability of a CO2 rotary‐arc load‐break switch

First, current interrupting experiments were performed for a rotary‐arc type of load‐break switch filled with pure CO₂ at a total pressure of 0.1 MPa. Increase in the coil turns for generating magnetic field from 1 to 1.8, 2.5, and 3.6 (arbitrary unit) raised the current interrupting capability from 2.6 kA to 3.2, 3.5, and 4.1 kA. Second, experiments were performed for CO₂ gas mixture under the condition of 3.6 coil turns. Gases of He, O₂, N₂, and air were admixted to CO₂. Adding either He or O₂ to CO₂ at a concentration of 30% allows the switch to have higher interrupting capability than using pure CO₂. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 21–27, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20742