Delayed labelling of brain glutamate after an intra-arterial [13C]glucose bolus: evidence for aerobic metabolism of guinea pig brain glycogen store.

Glycogen in glial cells is the largest store of glucose equivalents in the brain. Here we describe evidence that brain glycogen contributes to aerobic energy metabolism of the guinea pig brain in vivo. Five min after an intra-arterial bolus injection of d-[U-14C]glucose, 28+/-11% of the radioactivity in brain tissue was associated with the glycogen fraction, indicating that a significant proportion of labelled glucose taken up by the brain is converted to glycogen shortly after bolus infusion. Incorporation of 13C-label into lactate generated by brains made ischaemic after d-[1-13C]glucose injection confirms that these glucose equivalents can be mobilised for anaerobic glucose metabolism. Aerobic metabolism was monitored by following the time course of 13C-incorporation into glutamate in guinea pig cortex and cerebellum in vivo. After an intra-arterial bolus injection of d-[1-13C]glucose, glutamate labelling reached a maximum 40-60 min after injection, suggesting that a slowly metabolised pool of labelled glucose equivalents was present. As the concentration of 13C-labelled glucose in blood was shown to decrease below detectable levels within 5 min of bolus injection, this late phase of glutamate labelling must occur with mobilisation of a brain storage pool of labelled glucose equivalents. We interpret this as evidence that glucose equivalents in glycogen may contribute to energy metabolism in the aerobic guinea pig brain.     

Histological analysis of gonadal development in Patagonotothen tessellata (Richardson 1845) (Nototheniidae: Pisces) from the Beagle Channel, Argentina

Histological analysis of gonadal development in Patagonotothen tessellata (Richardson 1845) was carried out over a 3-year period (1987–1989) on samples from the Beagle Channel, Tierra del Fuego, Argentina. Testicular structure is defined as of the 'unrestricted spermatogonial type'. Maturation processes of cysts are synchronized in the various tubules. This degree of synchronization, as well as the characteristic of the different cellular types, permits definition of four spermatogenetic stages. Patagonotothen tessellata is defined as a total spawner according to ovocitary development and oocyte diameter frequency distribution analyses. Oocyte reabsorption and the likely consequences thereof on reproductive potential are also analysed. Patagonotothen tessellata is the first species of Nototheniids for which annual double spawning (winter and summer) and nonbiennial gonadal maturation processes are described.     

Constitutive relationship of tissue behavior with damage accumulation of human cortical bone

Microdamage accumulation has been identified as a major conduit for bone tissues to absorb fracture energy. Due to the poor understanding of its underlying mechanism, however, an adequate constitutive relationship between damage accumulation and the mechanical behavior of bone has not yet been established. In this study, the constitutive relationship between the damage accumulation induced by overload and the evolution of mechanical properties of bone with incremental deformation was established based on the experimental results obtained from a novel progressive loading protocol developed in our laboratory. First, a decayed exponential model was proposed to capture the damage accumulation (modulus loss) with increase in applied strain. Next, a power law function was proposed to represent the progression of plastic deformation with damage accumulation. Finally, a linear combination of the Kohlrausch–Williams–Watts (KWW) and the Debye functions was used to depict the viscoelastic behavior of bone associated with damage accumulation. The results of this study may help in developing a constitutive model for predicting the mechanical behavior of cortical bone tissues.     

Cellular immune responses and FAD-glucose dehydrogenase activity of Mamestra brassicae (Lepidoptera: Noctuidae) challenged with three species of entomopathogenic fungi

Abstract.  Cellular immune responses and glucose dehydrogenase activity are examined in the larvae of Mamestra brassicae (Lepidoptera: Noctuidae) injected with three entomopathogenic fungi, Beauveria bassiana , Nomuraea rileyi and Paecilomyces tenuipes . Total haemocyte count and the number of spherulocytes increase significantly over 2 h in larvae infected with N. rileyi , the most virulent fungal pathogen of M. brassicae . However, glucose dehydrogenase is not activated in the haemolymph of larvae inoculated with N. rileyi . By contrast, P. tenuipes , the least virulent fungal species, but with the highest proteolytic activity, activates glucose dehydrogenase and the number of nodules formed is significantly larger in larvae inoculated with P. tenuipes . It is suggested that the different virulence of each fungal species is caused by specific immune responses in the larvae. Haemopoiesis is affected by the fungal conidia and this is investigated by culture of the haemopoietic organs of M. brassicae in vitro . The proportion of spherulocytes discharged from the organs is typically high after all of the fungal treatments. In addition, the anterior and posterior haemopoietic organs, according to the histological locations in larva, show different patterns of haemopoiesis in response to fungi.     

Identification of the aspartimide structure in a previously-reported peptide

The octapeptide Leu-Ser-Arg-Leu-Phe-Asp-Asn-Ala (hGH 6-13) has been reported to show insulin-potentiating properties, and its synthesis by conventional solid-phase synthesis was previously described. It is now shown that peptide synthesized with diisopropylethylamine or N-methylmorpholine as neutralizing base in each cycle does have the above structure. When triethylamine was used as neutralizing base however, the Asp residue was converted to its imide, the presence of which has been demonstrated by means of infrared, 1H-NMR and fast-atom bombardment mass spectra, and by reactivity studies, electrophoresis at several pH values, and enzymic hydrolysis. Only the imide form of the peptide possesses the previously reported biological properties. A study of imide formation from protected and unprotected peptides showed that cyclization occurred during a wide range of acid and base treatments, but 10% triethylamine in CH2Cl2 was most effective, producing over 40% of imide in 90 min. The results of the investigation are compared with others in the literature, including those for the peptide hormone secretin.     

The localization of transport properties in the frog lens.

The selectivity of fiber-cell membranes and surface-cell membranes in the frog lens is examined using a combination of ion substitutions and impedance studies. We replace bath sodium and chloride, one at a time, with less permeant substitute ions and we increase bath potassium at the expense of sodium. We then record the time course and steady-state value of the intracellular potential. Once a new steady state has been reached, we perform a small signal-frequency-domain impedance study. The impedance study allows us to separately determine the values of inner fiber-cell membrane conductance and surface-cell membrane conductance. If a membrane is permeable to a particular ion, we presume that the conductance of that membrane will change with the concentration of the permeant ion. Thus, the impedance studies allow us to localize the site of permeability to inner or surface membranes. Similarly, the time course of the change in intracellular potential will be rapid if surface membranes are the site of permeation whereas it will be slow if the new solution has to diffuse into the intercellular space to cause voltage changes. Lastly, the value of steady-state voltage change provides an estimate of the lens' permeability, at least for chloride and potassium. The results for sodium are complex and not well understood. From the above studies we conclude: (a) surface membranes are dominated by potassium permeability; (b) inner fiber-cell membranes are permeable to sodium and chloride, in approximately equal amounts; and (c) inner fiber-cell membranes have a rather small permeability to potassium.     

<Emphasis Type="Italic">In Silico</Emphasis> Study on Retinoid-binding Modes in Human RBP and ApoD Lipocalins

Lipocalins are proteins with highly homologous structures but diverse sequences that are potential candidates for scaffold protein engineering with novel ligand-binding functions. Numerous crystal structures of lipocalin-ligand complexes have been identified and used in the study of their binding modes. On the other hand, crystallization studies cannot meet the increasing demand for novel lipocalin-ligand complexes in scaffold engineering, which requires rapid computational analyses of their binding modes in parallel. Human retinol-binding protein (RBP) and apolipoprotein D (apoD) are sequentially very distant proteins, but they show tight binding against retinoids, such as retinol and retinoic acid. In the present study, complexes of the two lipocalins with retinol and retinoic acid were modeled computationally by a molecular docking simulation, and their ligand-binding modes were analyzed at a molecular level. The models identified the crucial residues of lipocalins that interact with the ligands and revealed the similarities and differences in their retinoid-binding modes as well as in the specific interactions of the retinoid species within the same lipocalin. An analysis of the amino acid propensity of the retinoid-binding residues suggested that the evolutionary preference of the residues is restricted to the binding pocket rather than the entire protein. The distribution of charged residues around the terminus of retinoic acid showed a huge difference between RBP and ApoD, which might be a factor for the different binding affinities of lipocalins against retinoic acid. This in silico study is expected to be applied to scaffold protein engineering for novel retinoid-binding lipocalins.     

Large‐Scale Conductive Yarns Based on Twistable Korean Traditional Paper (Hanji) for Supercapacitor Applications: Toward High‐Performance Paper Supercapacitors

A simple and scalable method to fabricate a yarn‐type supercapacitor with a large specific capacitance without the aid of traditional pseudocapacitive electrode materials such as conducting polymers and metal oxides is reported. The yarn‐type supercapacitors are made from twisting reduced graphene oxide (rGO) or/and single‐walled carbon nanotubes (SWNTs)‐coated Korean traditional paper (KTP). The yarn‐type paper supercapacitor displays surprisingly enhanced electrochemical capacitance values, showing synergistic effect between rGO and SWNTs (500 times larger than performance of yarn‐type rGO‐coated paper supercapacitors). Coating rGO or/and SWNTs on KTP gives good morphology to the composite film, in which porosity increases and mean pore diameter decreases. The yarn‐type rGO/SWNT paper supercapacitor shows good mechanical strength, high flexibility, excellent electrochemical performance, and long‐life operation. The yarn‐type supercapacitor has an excellent electrochemical performance with a specific capacitance of 366 F g^?1 at scan rate of 25 mV s^?1 and high stability without any degradation in electrical performance up to 10 000 charge–discharge cycles. The average capacitance of rGO/SWNT@KTP yarn‐type supercapacitors is seven times higher than that of sheet‐type supercapacitors at scan rate of 500 mV s^?1. The lighting of a red light‐emitting diode (LED) is demonstrated by the yarn‐type paper supercapacitor without connecting supercapacitors in series.