GLUT-4 expression is not consistently higher in type-1 than in type-2 fibres of rat and human vastus lateralis muscles; an immunohistochemical study

In whole muscle homogenates, the glucose transporter-4 (GLUT-4) content is reported to be higher in muscles consisting predominantly of oxidative (type-1) muscle fibres than in muscles consisting predominantly of glycolytic (type-2) fibres. From these findings, it has been deduced that in rat muscle, oxidative fibres have an intrinsically higher level of GLUT-4 protein than glycolytic fibres. No data is available concerning human muscle. Moreover, the fibre-type-specific expression of GLUT-4 has not yet been examined directly. In this study, the relative abundance of GLUT-4 protein expression in individual fibres of different types within a muscle was compared directly in immunohistochemical assays. The human vastus lateralis muscle and a selection of rat muscles were studied using a novel GLUT-4 antiserum. It is concluded that the pattern of fibre-type-specific GLUT-4 expression differs between human and rats and varies between the different muscles studied, indicating that non-fibre-type-specific factor(s) affect expression of GLUT-4. The observation that within a muscle a fibre-type-specific expression of GLUT-4 was observed indicates that fibre-type-specific factors contribute to GLUT-4 expression as well. Thus, it can be postulated that both fibre-type-dependent and fibre-type-independent factors affect GLUT-4 expression.     

Zur Katalyse der stereospezifischen Butadienpolymerisation mit den Katalysatorsystemen aus Nd(η3-C3H5)3 · dioxan und methylaluminoxan (MAO) sowie Hexaisobutylaluminoxan (HIBAO)

The activation of the tris(allyl)neodymium complex Nd(η³-C₃H₅)₃ · dioxane with alkylaluminoxanes (MAO or HIBAO) results in highly selective catalysts for the 1,4-cis-polymerization of butadiene (cis-selectivity up to 80%). Under standard conditions (50°C, toluene), the turnover frequency (TOF) of the catalyst/MAO system amounts to 10–15000 mol butadiene/(mol Nd · h). Molecular weight determinations indicate the formation of only one polymer chain per neodymium center as in a living polymerization reaction, and for the catalyst/HIBAO system the rate law r_p = k_p [Nd][C₄H₆] with k_p = 8,7 · 10^?2 mol/(L · s) (at 25°C) has been derived. As the catalytically active species, a cationic monobutenyl neodymium(III) complex is discussed, which is stabilized through coordinative interaction with the counter anion as well as the growing polybutadiene chain. This cationic complex reacts under insertion with butadiene in a bimolecular fashion.     

Mechanics of porcine coronary arteries<Emphasis Type="Italic">ex vivo</Emphasis> employing impedance planimetry: A new intravascular technique

Our objective was to evaluate methodological aspects of impedance planimetry, a new balloon catheter-based technique, for the investigation of coronary artery mechanical wall properties. We used a four ring-electrode electrical impedance measuring system that was located inside a balloon. Two of the electrodes were used for excitation and connected to a generator producing a constant alternating current of 250 mA at 5 kHz. The other two electrodes for detection were placed midway between the excitation electrodes. The balloon was distended with electrically conducting fluid through an infusion channel. The vessel cross-sectional area (CSA) was measured according to the field gradient principle by measuring the impedance of the fluid inside the balloon. Impedance planimetry was applied in the three major branches of the coronary arteries of seven extracted porcine hearts to assess luminal CSAs in response to internal pressurization. The biomechanical wall properties were evaluated by computing the strain [(r?r ₀)·r ₀ ^?1, wherer is the vessels inner radius computed as (CSA · π^?1)^½ andr ₀ is the radius of the vessel at a minimal distension pressure], the tension [(r·dP), wheredP is the transmural pressure difference], and the pressure elastic modulus (ΔP·r·Δr ^?1). We found thatin vitro testing demonstrated that impedance planimetry was accurate and reproducible. The technique has controllable sources of crror. Measurements were performed with consecutively increasing pressures in the range 1–25 kPa (8–188 mmHg, 0.01–0.25 atm). The CSAs increased nonlinearly and were significantly larger in the left anterior descendent coronary artery (LAD) (1 kPa, mean 5.0 mm²; 25 kPa, mean 21.8 mm²) than in both the left circumflex (Cx) (4.5–16.0 mm²) and the right coronary artery (RCA) (2.8–15.6 mm²) (analysis of variance,P<0.001 for both). The circumferential wall tension-strain relation showed exponential behavior. For a given strain, tension values for LAD were significantly lower than those of Cx (P<0.01). The pressure elastic modulus-strain relation also was exponential, and values for Cx were significantly lower than values for LAD (P<0.001) and RCA (P<0.05). Impedance planimetry was applied to the study of coronary artery biomechanicsex vivo. The LAD had the largest CSA, and the Cx was the least compliant. Methodological aspects of anin vivo introduction of the method require additional evaluation.     

A case of 46,XX,r(X) (p1q1) diagnosed by in situ hybridization

A small marker chromosome was identified as an X-derived ring chromosome by in situ hybridization with a biotinylated X-chromosome specific a-satellite DNA probe. This procedure clearly determined the chromosomal origin of the marker chromosome, which had been impossible to define by conventional cytogenetic techniques including high resolution banding.     

Tissue reactions of in situ formed dextran hydrogels crosslinked by stereocomplex formation after subcutaneous implantation in rats

In this study, the in vivo biocompatibility of physically crosslinked dextran hydrogels was investigated. These hydrogels were obtained by mixing aqueous solutions of dextran grafted with L-lactic acid oligomers and dextran grafted with D-lactic acid oligomers. Gelation occurs due to stereocomplex formation of the lactic acid oligomers of opposite chirality. Since gelation takes some time, in situ gel formation is possible with this system. A number of sterilization methods was evaluated for their effect on the chemical and physical properties of the hydrogel. It was shown that of the investigated options (filtration, gamma irradiation, dry-heat and autoclaving) dry-heat sterilization was the preferred method to prepare sterile gels suitable for in vivo evaluations. Two types of stereocomplex gels were prepared and implanted subcutaneously in rats. The tissue reaction was evaluated over a period of 30 days. A mild ongoing foreign body reaction was observed characterized by infiltration of macrophages. Giant cells were only scarcely formed and the low numbers of lymphocytes showed that priming of the immune system is hardly involved. Importantly, the gels fully degraded in vivo within 15 days, which is in good agreement with the in vitro degradation behaviour of these gels. In conclusion, stereocomplexed dextran-oligolactic gels showed good biocompatibility which makes them suitable candidates for the design of controlled release devices for pharmaceutically active proteins.     

Corticospinal excitability during laughter: implications for cataplexy and the comparison with REM sleep atonia

Cataplexy is usually seen as rapid eye movement (REM) sleep atonia occurring at an inopportune moment. REM sleep atonia is the result of postsynaptic inhibition, i.e. inhibition of alpha motor neurones. Although this may explain the suppression of H-reflexes during REM sleep, cataplexy and laughter, it is not the only explanation. Presynaptic inhibition, in which afferent impulses are prevented from reaching motor neurones, is an alternative. Testing H-reflexes and magnetic-evoked potentials (MEPs) helps to tell them apart: in postsynaptic inhibition MEPs and H-reflexes change in tandem, while H-reflexes may decrease independent of MEPs with other inhibition modes. We studied motor inhibition during laughter, the strongest trigger for cataplexy. H-reflexes were evoked every 2 s in the soleus muscle in 10 healthy subjects watching comical video fragments. MEPs were evoked when H-reflexes decreased during laughter, and, as a control, when subjects did not laugh. Pairs of MEPs and the immediately preceding H-reflexes were studied. Compared with the control condition, laughter caused mean MEP area to increase by 60% (P=0.006) and mean H-reflex amplitude to decrease by 33% (P=0.008). This pattern proves that postsynaptic inhibition cannot have been the sole influence. The findings do not prove which mechanisms are involved; one possibility is that the decrease in H-reflex amplitude was the result of presynaptic inhibition, and that cortical and/or spinal facilitation accounted for increased MEPs. Regardless, the pattern differs fundamentally from the reported mechanism of REM sleep atonia. Existing scanty data on cataplexy suggest a pattern of H-reflexes and MEPs similar to that during laughter, but this needs further study.     

The PTPN22 R620W polymorphism associates with RF positive rheumatoid arthritis in a dose-dependent manner but not with HLA-SE status

We have recently described the association between rheumatoid arthritis and a coding single-nucleotide polymorphism in the intracellular protein tyrosine phosphatase, PTPN22. The disease-associated polymorphism, 1858 C/T (rs2476601), encodes an amino-acid change (R620W) in one of four SH3 domain binding sites in the PTPN22 molecule. We have now extended our initial studies to address three questions: (1) Is the association with rheumatoid arthritis limited to rheumatoid factor (RF) positive disease? (2) Does homozygosity for PTPN22 R620W substantially increase disease susceptibility? (3) Is there an interaction between PTPN22 and the rheumatoid arthritis (RA)-associated HLA-DRB1 shared epitope alleles? A total of 1413 Caucasian rheumatoid arthritis patients and 1401 Caucasian controls were genotyped. The results support the view that PTPN22 was strongly and preferentially associated with RF positive disease (OR=1.75, 95% CI 1.46-2.10, P=1.3 x 10(-9)). The PTPN22 risk allele was not significantly associated with RF negative disease (OR=1.19, 95% CI 0.92-1.53, P=0.18), although a very weak association cannot be completely excluded. There was a strong dose effect on disease risk; two copies of the PTPN22 R620W allele more than doubles the risk for RF positive RA (OR=4.57, 95% CI 2.35-8.89). There was no evidence of a genetic association between PTPN22 and HLA susceptibility alleles.     

β1-Adrenoceptor gene variations: a role in idiopathic dilated cardiomyopathy?

A substantial body of evidence suggests involvement of the human beta1-adrenoceptor (beta1-AR) gene in the pathophysiology of dilated cardiomyopathy (DCM), a severe heart disease of significant public health impact. Beta1-AR-mediated signal transduction is dramatically altered due to downregulation, resulting in an impairment of myocardial response. The important role of genetic factors in idiopathic dilated cardiomyopathy (IDCM) recently recognized, we analyzed this prime candidate gene for genetic variation in carefully selected patients and controls. In this preliminary study, 18 single nucleotide polymorphisms were observed, 17 of which were located in the N-terminal and C-terminal region of the coding exon, resulting in 7 amino acid exchanges: Ser-49-Gly, Ala-59-Ser, Gly-389-Arg, Arg-399-Cys, His-402-Arg, Thr-404-Ala, and Pro-418-Ala. These mutations resulted in 11 different beta1-AR genotypes. Importantly, the genotypes carrying the Ser-49-Gly mutation in the N-terminus of the molecule in a heterozygous or homozygous form were observed significantly more frequently in the group of IDCM patients. The present results may provide a clue on the molecular mechanisms involved in IDCM, and add moreover interesting information on nature, distribution, and evolutionary aspects of sequence variation in human adrenergic receptor genes.     

Synthesis of frequency doubling polymeric materials, 1. Second-order nonlinear optical properties of poled chromophore-functionalized polymethacrylates

The synthesis and second harmonic coeficients d₃₃, d ₃₁ and the susceptibilities χ⁽²⁾ are reported of three series of (co)polymethacrylates that possess 4-(2,2-dicyanovinyl)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-N,N-dialkylaniline (P₁ and P₂), 4-(2,2-dicyanovinyl)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-(-piperidino)benzene (P₅ and P₆) and 4-(2,2-dicyano)- or 4-(2-cyano-2-methoxycarbonyl)vinyl-1-alkoxybenzene (P₃ and P₄) dyes

1 System. names of the monomers see Exptl. part.

. The second-order nonlinear optical properties of corona-poled aligned polymer films were evaluated by second harmonic generation measurements. The χ values for the P₁ and P₂ polymers vary from 58 to 318, respectively 32 to 106 · 10^?9 esu, for P₃ and P₄ from 7,6 to 19, respectively 4,4 to 7,4 · 10 ^?9 esu and for P₅ and P₆ from 219 to 42,8 respectively 28,1 to 8,1 · 10^?9 esu, depending on the dye chromophore concentration incorporated in the polymer structure.     

食管分层应力-应变研究

目的　探讨食管壁各层环向应力 应变分布特征。方法　将 8只Wister大鼠的食管标记、测量在体长度后剪下置于去钙离子Krebs液中。剪下标记的中段食管用做充压试验 ,将其在显微镜下分离成内层食管 (粘膜和粘膜下层 )和外层食管 (固有肌层 )。充压时全层和分层食管均被拉长至在体长度 ,以每分钟升高 2cmH2 O速度匀速充压。根据所测图像的几何数据计算全层和分层食管的Kirchhoff应力和Green应变。零应力状态作为计算应力和应变的基本参照状态。结果　 (1 )食管离体后较在体长度缩短 2 4%。 (2 )全层食管和分层食管的环向应力 应变曲线均符合指数方程τ =(τ +β)eα(ε-ε ) -β(判定系数 >0 .96) ,为非线性关系。 (3 )与全层食管相比 ,分层后内层食管应力 应变曲线较陡直 ,且移向左侧 ,差别有统计意义 (P <0 .0 5 ) ,外层食管的曲线移向右侧 ,差别无统计意义 (P >0 .0 5 ) ,内外两层食管的应力 -应变曲线亦有统计差别 (P <0 .0 5 )。结论　食管壁各层环向应力 -应变均符合非线性关系 ,食管内层不如外层易变形