Association between Poor Glycemic Control,Impaired Sleep Quality,and Increased Arterial Thickening in Type 2 Diabetic Patients

Objective

Poor sleep quality is an independent predictor of cardiovascular events. However, little is known about the association between glycemic control and objective sleep architecture and its influence on arteriosclerosis in patients with type-2 diabetes mellitus (DM). The present study examined the association of objective sleep architecture with both glycemic control and arteriosclerosis in type-2 DM patients.

Design

Cross-sectional study in vascular laboratory.

Methods

The subjects were 63 type-2 DM inpatients (M/F, 32/31; age, 57.5±13.1) without taking any sleeping promoting drug and chronic kidney disease. We examined objective sleep architecture by single-channel electroencephalography and arteriosclerosis by carotid-artery intima-media thickness (CA-IMT).

Results

HbA1c was associated significantly in a negative manner with REM sleep latency (interval between sleep-onset and the first REM period) (β=-0.280, p=0.033), but not with other measurements of sleep quality. REM sleep latency associated significantly in a positive manner with log delta power (the marker of deep sleep) during that period (β=0.544, p=0.001). In the model including variables univariately correlated with CA-IMT (REM sleep latency, age, DM duration, systolic blood pressure, and HbA1c) as independent variables, REM sleep latency (β=-0.232, p=0.038), but not HbA1c were significantly associated with CA-IMT. When log delta power was included in place of REM sleep latency, log delta power (β=-0.257, p=0.023) emerged as a significant factor associated with CA-IMT.

Conclusions

In type-2 DM patients, poor glycemic control was independently associated with poor quality of sleep as represented by decrease of REM sleep latency which might be responsible for increased CA-IMT, a relevant marker for arterial wall thickening.     

Extracellular Signal-regulated Kinase and Glycogen Synthase Kinase 3β Regulate Gephyrin Postsynaptic Aggregation and GABAergic Synaptic Function in a Calpain-dependent Mechanism

Molecular mechanisms of plasticity at GABAergic synapses are currently poorly understood. To identify signaling cascades that converge onto GABAergic postsynaptic density proteins, we performed MS analysis using gephyrin isolated from rat brain and identified multiple novel phosphorylation and acetylation residues on gephyrin. Here, we report the characterization of one of these phosphoresidues, Ser-268, which when dephosphorylated leads to the formation of larger postsynaptic scaffolds. Using a combination of mutagenesis, pharmacological treatment, and biochemical assays, we identify ERK as the kinase phosphorylating Ser-268 and describe a functional interaction between residues Ser-268 and Ser-270. We further demonstrate that alterations in gephyrin clustering via ERK modulation are reflected by amplitude and frequency changes in miniature GABAergic postsynaptic currents. We unravel novel mechanisms for activity- and ERK-dependent calpain action on gephyrin, which are likely relevant in the context of cellular signaling affecting GABAergic transmission and homeostatic synaptic plasticity in pathology.     

Interaction with metal salts of homopolymer or copolymers of a vinyl compound carrying linear tripeptide as a substituent

A vinyl compound carrying a linear tripeptide as a substituent, $\text{t-butyloxycarbonylsarcosyl}\text{-N}{}^{\mathrm{?}}\text{-}\text{acryloyl-}\text{l}\text{-lysylsarcosine}$ ethyl ester (Boc-Sar-N^?-AcrLys-Sar-OEt) (LP), was synthesized. By radical polymerization, the homopolymer (PLP) and the copolymers with styrene [P(LP-ST)] or 4-vinylpyridine [P(LP-VP)] of Boc-Sar-N^?-AcrLys-Sar-OEt were synthesized. The interaction of the homopolymer and the copolymers with alkali or alkaline-earth metal salts in nonpolar organic solvents was investigated. PLP showed a higher complexation ability towards alkali and alkaline-earth metal salts than the corresponding linear tripeptide, which indicates the enhancement of the complexation ability by the intramolecular cooperation of the linear tripeptide substituents in PLP. The interaction of P(LP-ST) with metal salts was much weaker than PLP, which indicates an inhibitory effect of styrene units upon the intramolecular cooperation of the linear tripeptide substituents. The interaction of P(LP-VP) with metal salts was much stronger than PLP, indicating a cooperation of pyridyl group for the coordination of the linear tripeptide ligand with metal ion. The permeation of metal salt across a blend film of cellulose acetate and PLP was enhanced by blending PLP and fastest for K⁺, indicating a participation of PLP in the ion transport. The permeation of metal salt across a blend film of cellulose acetate and P(LP-ST) was decelerated by blending P(LP-ST) and did not show any ion selectivity, reflecting the hydrophobicity and the low ability of complexation of P(LP-ST) copolymer. The permeation of metal salt across a blend film of cellulose acetate and P(LP-VP) was decelerated by blending P(LP-VP) and did not show any ion selectivity, although P(LP-VP) copolymer is very hydrophilic and strongly coordinative to metal salt. This anomaly may be a reflection of ion trapping by the P(LP-VP) component.     

Anatomical study of the venous drainage architecture of the scapular skin and subcutaneous tissue.

Venous anatomy of the skin and subcutaneous adipofascial tissue in the scapular region was examined in 14 specimens of 12 fresh cadavers that had been injected systemically with contrast medium. Three-dimensional analysis was performed by radiographing the specimens stereoscopically and splitting them into the skin and subcutaneous adipofascial tissue layers. From the architecture, most of the venous blood that had perfused the dermis was considered to pool in a polygonal venous network, located in the skin layer; to flow chiefly through some large communicating veins; and to enter the scapular, parascapular, or circumflex scapular veins. Most of the venous blood that had perfused the subcutaneous adipofascial tissue was considered to enter the scapular or parascapular veins directly.     

A third photoreceptor-specific GRK found in the retina of Oryzias latipes (Japanese killifish)

We previously reported that the teleost fish medaka (Oryzias latipes, Japanese killifish), possesses two kinds of G protein-coupled receptor kinases (GRKs) in the retina with different localizations: GRK7 (OlGRK-C) in cones and GRK1 (OlGRK-R1) in rods. To further clarify the diversity of teleost photoreceptor GRKs, we sought other medaka GRKs. We found an additional cDNA that encodes a second retina-specific GRK1 (OlGRK-R2). In situ hybridization experiments demonstrated that OlGRK-R2 mRNA is selectively expressed in rods. Sequence analysis of the Fugu rubripes genomic database unveiled a larger diversity of GRKs than previously expected. We also describe the light-dependent regulation of GRK1, a phenomenon that has not been found in other species. Immunocytochemical analysis indicated that OlGRK-R2 is localized in rod outer segments, independent of light condition. OlGRK-R1 is localized in the rod inner segments and synaptic termini of dark-adapted eyes, and moves to rod outer segments after light adaptation. Our studies suggest that the two medaka GRKs are not functionally redundant, and demonstrate a complicated light-dependent regulation of GRK1 in vivo.     

Two-photon microscopy: shedding light on the chemistry of vision

Two-photon microscopy (TPM) has come to occupy a prominent place in modern biological research with its ability to resolve the three-dimensional distribution of molecules deep inside living tissue. TPM can employ two different types of signals, fluorescence and second harmonic generation, to image biological structures with subcellular resolution. Two-photon excited fluorescence imaging is a powerful technique with which to monitor the dynamic behavior of the chemical components of tissues, whereas second harmonic imaging provides novel ways to study their spatial organization. Using TPM, great strides have been made toward understanding the metabolism, structure, signal transduction, and signal transmission in the eye. These include the characterization of the spatial distribution, transport, and metabolism of the endogenous retinoids, molecules essential for the detection of light, as well as the elucidation of the architecture of the living cornea. In this review, we present and discuss the current applications of TPM for the chemical and structural imaging of the eye. In addition, we address what we see as the future potential of TPM for eye research. This relatively new method of microscopy has been the subject of numerous technical improvements in terms of the optics and indicators used, improvements that should lead to more detailed biochemical characterizations of the eyes of live animals and even to imaging of the human eye in vivo.     

Selection of Rodent Species Appropriate for mtDNA Transfer to Generate Transmitochondrial Mito-Mice Expressing Mitochondrial Respiration Defects

Previous reports have shown that transmitochondrial mito-mice with nuclear DNA from Mus musculus and mtDNA from M. spretus do not express respiration defects, whereas those with mtDNA from Rattus norvegicus cannot be generated from ES cybrids with mtDNA from R. norvegicus due to inducing significant respiration defects and resultant losing multipotency. Here, we isolated transmitochondrial cybrids with mtDNA from various rodent species classified between M. spretus and R. norvegicus, and compared the O₂ consumption rates. The results showed a strong negative correlation between phylogenetic distance and reduction of O₂ consumption rates, which would be due to the coevolution of nuclear and mitochondrial genomes and the resultant incompatibility between the nuclear genome from M. musculus and the mitochondrial genome from the other rodent species. These observations suggested that M. caroli was an appropriate mtDNA donor to generate transmitochondrial mito-mice with nuclear DNA from M. musculus. Then, we generated ES cybrids with M. caroli mtDNA, and found that these ES cybrids expressed respiration defects without losing multipotency and can be used to generate transmitochondrial mito-mice expressing mitochondrial disorders.     

Effects of bulkiness and hydrophobicity of an aliphatic amino acid in the recognition helix of the GAGA zinc finger on the stability of the hydrophobic core and DNA binding affinity

The GAGA factor of Drosophila melanogaster uses a single Cys 2His 2-type zinc finger for specific DNA binding. The conformation and DNA binding mode of the GAGA zinc finger are similar to those of other structurally characterized zinc fingers. In almost all Cys 2His 2-type zinc fingers, the fourth position of the DNA-recognizing helix is occupied by the Leu residue involved in the formation of the minimal hydrophobic core. However, no systematic study on the precise role of the Leu residue in the hydrophobic core formation and DNA binding function has been reported. In this study, the Leu residue is substituted with other aliphatic amino acids having different side chain lengths and hydrophobicities, namely, Ile, Val, Aib, and Ala. The metal binding properties were studied by UV-vis spectroscopy. The peptide conformations were examined by CD and NMR spectroscopies. Furthermore, the DNA binding ability was examined with a gel mobility shift assay. Though the Ile, Val, and Aib mutants exhibited conformations similar to those of the wild type, the DNA binding affinity decreased as the side chain length of the amino acid decreased. Interestingly, the Val mutant can bind to the cognate DNA, while Aib cannot, in spite of the similarity in their secondary structures based on the CD measurements. Variable-temperature NMR experiments clearly indicated differences in the stability of the hydrophobic core between the Val and Aib mutants. This study demonstrates that the bulkiness of the conserved aliphatic residue is important in the formation of the well-packed minimal hydrophobic core and proper ternary structure and that the hydrophobic core stabilization is apparently related to the DNA binding function of the GAGA zinc finger.