Circular polarization in the optical afterglow of GRB 121024A.

Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.

Comparative analyses of paediatric dental measurements using plaster and three-dimensional digital models.

AIM: Recent advances in three-dimensional imaging have led to an increased interest in the application of computer-models in paediatric dentistry. However, in evidence-based paediatric dentistry the accuracy of new methods must be validated before they are introduced to clinical practice. We aimed to compare the accuracy of measurements of digital models obtained using a non-contact 3D measuring system, with direct measurements made on plaster models (gold standard) from children. MATERIALS AND METHODS: Twelve pairs of plaster models were obtained from children with deciduous dentition; tooth size, arch width, and arch length were examined. The same parts on each cast were measured twice with at least a 2-week interval between measurements with each method by four examiners. Linear mixed-effects model analyses were performed for comparison of values from the 2 different measurement methods. RESULTS: The average difference between the 2 methods in measured values, derived from the final model, was <0.2 mm. Random effect of examiners was always the smallest component of variance, and frequently negligible. STATISTICS: Intraclass correlation coefficients were typically >90%. CONCLUSION: These results suggest that primary dentition analysis of digital models has a high accuracy level, comparable to that of direct measurement of plaster models by digital calipers.

Coherence between cortical and muscular activities after subcortical stroke.

BACKGROUND AND PURPOSE: Functional connection between the motor cortex and muscle can be measured by electroencephalogram-electromyogram (EEG-EMG) coherence. To evaluate the functional connection to muscle between contralateral and ipsilateral motor cortices after pyramidal tract lesions, we investigated 6 patients with chronic subcortical stroke. METHODS: High-resolution EEG and EMG of the hand, forearm, and biceps muscles were recorded during 3 tonic contraction tasks: (1) elbow flexion, (2) wrist extension, and (3) power grip. To evaluate the cortical control of EMG, EEG-EMG coherence was computed. RESULTS: EEG-EMG coherence was localized over the contralateral sensorimotor area in all circumstances, and there was no significant coherence at the ipsilateral side. EEG-EMG coherence was significantly smaller on the affected side for the hand and forearm muscles but not for the biceps muscle. CONCLUSIONS: All direct functional connections to muscle after recovered subcortical stroke come from the contralateral motor cortex. The different effects of the lesion on the proximal and distal muscles appear to be associated with the strength of the corticospinal pathway.

Fiber type composition of the vastus lateralis muscle of young men and women.

This study presents data collected over the past 10 years on the muscle fiber type composition of the vastus lateralis muscle of young men and women. Biopsies were taken from the vastus lateralis muscle of 55 women (21.2+/-2.2 yr) and 95 men (21.5+/-2.4 yr) who had volunteered to participate in various research projects. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were classified using mATPase histochemistry, and cross-sectional area was measured for the major fiber types (I, IIA, and IIB). Myosin heavy chain (MHC) content was determined electrophoretically on all of the samples from the men and on 26 samples from the women. With the exception of fiber Type IC, no significant differences were found between men and women for muscle fiber type distribution. The vastus lateralis muscle of both the men and women contained approximately 41% I, 1% IC, 1% IIC, 31% IIA, 6% IIAB, and 20% IIB. However, the cross-sectional area of all three major fiber types was larger for the men compared to the women. In addition, the Type IIA fibers were the largest for the men, whereas the Type I fibers tended to be the largest for the women. Therefore, gender differences were found with regard to the area occupied by each specific fiber type: IIA>I>IIB for the men and I>IIA>IIB for the women. These data establish normative values for the mATPase-based fiber type distribution and sizes in untrained young men and women.

Effects of high-intensity resistance training on untrained older men. I. Strength, cardiovascular, and metabolic responses.

Most resistance training studies of older subjects have emphasized low-intensity, short-term training programs that have concentrated on strength measurements. The purpose of this study was, in addition to the determination of strength, to assess intramuscular and transport factors that may be associated with strength increments. Eighteen untrained men ages 60-75 years volunteered for the study; 9 were randomly placed in the resistance-training group (RT), and the other half served as untrained (UT) or control subjects. RT subjects performed a 16-week high-intensity (85-90% 1 repetition maximum (RT]) resistance training program (2 x/wk) consisting of 3 sets each to failure (6-8 repetitions based on 1 RM of 3 exercises): leg press (LP), half squat (HS), and leg extension (LE) with 1-2 minutes rest between sets. Pre- and post- training strength was measured for the 3 training exercises using a 1 RM protocol. Body fat was calculated using a 3-site skinfold method. Biopsies from the vastus lateralis m. were obtained for fiber type composition, cross-sectional area, and capillarization measurements. Exercise metabolism, electrocardiography, and arterial blood pressure were observed continuously during a progressive treadmill test, and resting echocardiographic data were recorded for all subjects. Pre- and post-training venous blood samples were analyzed for serum lipids. Resistance training caused significant changes in the following comparisons: % fat decreased in the RT group by almost 3%, strength improved for all exercises: LE = + 50.4%, LP = + 72.3%, HS = + 83.5%; type IIB fibers decreased and IIA fibers increased; cross-sectional areas of all fiber types (I, IIA, IIB) increased significantly, and capillary to fiber ratio increased but not significantly. No differences were noted for ECG and echocardiographic data. The RT group significantly improved treadmill performance and VO2max. Pre- and post-training serum lipids improved but not significantly. No significant changes occurred in any pre- to post-tests for the UT group. The results show that skeletal muscle in older, untrained men will respond with significant strength gains accompanied by considerable increases in fiber size and capillary density. Maximal working capacity, VO2max, and serum lipid profiles also benefited from high-intensity resistance training, but no changes were observed for HR max, or maximal responses of arterial blood pressure. Older men may not only tolerate very high intensity work loads but will exhibit intramuscular, cardiovascular, and metabolic changes similar to younger subjects.

Subregions of human MT complex revealed by comparative MEG and direct electrocorticographic recordings.

OBJECTIVE: To locate the visual motion complex (MT+) and study its response properties in an epilepsy surgery patient. METHODS: A 17-year-old epilepsy patient underwent invasive monitoring with subdural electrodes in the right temporo-parieto-occipital area. MT+ was investigated by cortical electric stimulation and by epicortical visual evoked potentials time-locked to motion onset of sinusoidal gratings (motion VEP). Motion-related visual evoked magnetic field (motion VEF) was also recorded before the electrode implantation to complement the invasive recording. RESULTS: Motion VEPs revealed two subregions within MT+, generating early and late potentials respectively. The early activity with a peak around 130 ms was localized at a single electrode situated immediately caudal to the initial portion of the ascending limb of the superior temporal sulcus (AL-STS). The late activity, peaking at 242-274 ms, was located ventro-rostrally over three electrodes. Among the four electrodes with motion VEPs, cortical stimulation at the most caudal pair elicited motion-in-depth perception involving the whole visual field. In addition to two subregions revealed on the gyral crown, magnetoencephalography (MEG) demonstrated another subregion with a late motion VEF in AL-STS immediately rostral to the electrode with the early motion VEP. CONCLUSIONS: In combination with MEG recording, the present invasive exploration demonstrated human MT+ in a focal area of the temporo-parieto-occipital junction and delineated possible three subregions as indicated by the different latencies and distributions of the motion VEP/VEFs. SIGNIFICANCE: Comparative MEG and direct electrocorticographic recordings delineated possible subregions within the human MT complex.

Ageing, but not yet senescent, rats exhibit reduced muscle quality and sarcoplasmic reticulum function.

AIM: Reduced muscle force greater than expected from loss of muscle mass has been reported in ageing muscles. Impaired sarcoplasmic reticulum (SR) Ca(2+) release has been implicated as a possible mechanism, and attributed to several factors, including loss of ryanodine receptor (RYR) expression and protein binding. The aim of this study was to evaluate muscle quality and SR Ca(2+) release in ageing rats that were not so old that major atrophy had occurred. METHODS: We collected in situ force data from the plantarflexor muscle group and muscle mass from the constituent muscles to determine muscle quality (force/mass) in adult (6-8 months) and ageing (24 months) rats (n=8/group). We evaluated SR Ca(2+) uptake and release, and determined expression of key proteins associated with Ca(2+) release [RYR and FK506 binding protein (FKBP)] and uptake (SERCA, parvalbumin, calsequestrin). RESULTS: Plantarflexor force and muscle quality were reduced with ageing (approx. 28 and 34%, respectively), but atrophy was limited, and significant only in the medial gastrocnemius (approx. 15%). The fast phase of SR Ca(2+) release was reduced with ageing in both gastrocnemii, as was FKBP expression and FKBP-RYR binding, but RYR expression was not affected. Similar, but non-significant changes were present in the plantaris, but the soleus muscle generally showed no ageing-related changes. CONCLUSION: These data suggest a possible role for impaired SR Ca(2+) release in ageing-related loss of muscle quality, although not through loss of RYR expression.

Calcium enhanced delivery of tetraarginine-PEG-lipid-coated DNA/protamine complexes.

As we have previously reported the delivery of plasmid DNA (DNA) complexed with oligoarginine-PEG artificial lipids (oligoarginine/DNA complexes), we focused on tetra- and decaarginine (Arg4, Arg10) to improve transfection efficiency by both the formation of oligoarginine-coated DNA complexed with protamine (PD), and the addition of Ca(2+) after formation of complexes. The efficiency of DNA condensation was determined by gel electrophoresis. Cellular uptake and transfection efficiency were evaluated in human cervical carcinoma HeLa cells using flow cytometry and luciferase assay. Oligoarginine-coated PD enhanced transfection efficiency significantly more than complexes where Arg10 in both vectors exhibited higher transfection efficiency than Arg4. As assessed by gel retardation assay, high gene expression by Arg10 may be explained by Arg4 binding DNA more strongly than Arg10. The addition of Ca(2+) to incubation medium increased transfection efficiency of Arg4-coated PD 70-fold, similar to that of Arg10-coated PD alone without an increase of cellular uptake, suggesting that Ca(2+) induced the release of DNA from complexes in endosomes. Only Arg4 with low cytotoxicity could gain an advantage from Ca(2+) in transfection, but Arg10 with relatively high cytotoxicity could not. The present results demonstrate that Arg4-coated PD with Ca(2+) has great potential as an efficient non-viral vector with low toxicity.

Number of residues in a sphere around a certain residue can be used as a hydrophobic penalty function of proteins.

A novel hydrophobic penalty function of proteins is proposed and assessed with several test cases. The number of residues in a defined sphere around a certain residue is averaged over the data set proteins. Differences between the standard values thus obtained and calculated values are summed up, residue by residue, with the weight of standard deviations to give the penalty value. This penalty function is applied to the structures of randomly shuffled sequences, incorrectly folded structures and partially denatured structures displayed on a graphics terminal, and is shown to discriminate the native structure from others fairly well, although the present parameter set is tuned for proteins of about 100-150 residues. From the results of present study and the known correlation with other hydrophobic parameters of amino acids, the penalty function can be considered as a practical amino acid residue-level hydrophobic penalty function.

Protein three-dimensional structure generation with an empirical hydrophobic penalty function.

Given current computational environments, it is worthwhile to establish amino acid residue-level functions which approximate protein folds quite well. Such functions must be the interim steps toward protein three-dimensional structure prediction. I have shown that an empirical hydrophobic penalty function of protein, derived from the number of residues in a sphere around each residue, could be utilized to distinguish the correctly folded structure from the incorrect ones. In order to assess the predictive power of the penalty function, I have generated conformations by randomly changing main chain dihedral angles, and applied the penalty function to them. If only a local region was allowed to change its conformation, native-like structures could be generated within a reasonable computational time. In global simulations, however, a considerable number of nonnative conformations, which gave as small a penalty value as that of the native protein, were found. Although some of the conformations were compact and globular, they were quite different from the native structure in that they lacked most of the secondary structures. This result shows that the penalty function alone cannot define the native structure, and that substructure information may help the penalty function to reach the correctly folded structure.

Mapping active sites of blood coagulation serine proteases--activated protein C and thrombin--on simple graphics models.

Employing the known three-dimensional (3D) structure of trypsin, we constructed simple graphics models of human-activated protein C and thrombin catalytic domains. Considering the structural analysis of bovine trypsin and pancreatic trypsin inhibitor complex, the difference of active-site amino acid sequences of human protein C inhibitor and antithrombin III and their inhibitory selectivity toward activated protein C and thrombin, we estimated the enzymatic subsites of activated protein C and thrombin and mapped them on the graphics models. Predicted favorable contacts can explain substrate selectivity of the enzymes. In this study, we used two types of modified ALPHA representations extensively. Since almost no report on the 3D structure of a blood coagulation factor has appeared and even an extensive molecular mechanics or dynamics calculation cannot produce satisfying results, simple graphics representation has several advantages.

Nucleotide sequences of the genes for two distinct cephalosporin acylases from a Pseudomonas strain.

Two genes, acyI and acyII, for distinct cephalosporin acylases from Pseudomonas sp. strain SE83 (A. Matsuda, K. Matsuyama, K. Yamamoto, S. Ichikawa, and K.I. Komatsu, J. Bacteriol. 169:5815-5820, 1987) were sequenced. Each sequence contained a single open reading frame for two nonidentical subunits, predicting a common precursor. Some homologies at the amino acid level were found between the acyII-encoded enzyme, but not the acyI-encoded one, and other related acylases.

Structure prediction of protease inhibitor region in amyloid precursor protein of Alzheimer's disease.

Recent findings of the protease inhibitor domain in amyloid precursor protein of Alzheimer's disease (APPI) raised a novel hypothesis on the mechanism of amyloid deposition in the brain. APPI has significant amino acid sequence homology with Kunitz-type basic trypsin inhibitor super-family proteins, and the gene expression product showed real inhibitory activity. Since the three-dimensional model of APPI would help in understanding biological phenomena in molecular detail, we constructed an atomic model of APPI based on the structure of bovine pancreatic trypsin inhibitor (BPTI). The substitution of BPTI side chains by best-fitting corresponding amino acid structures was followed by the removal of van der Waals overlappings by molecular mechanics energy minimization with the AMBER force field, to give the feasible model of APPI. We also built serine protease models based on the structure of trypsin and investigated the target enzyme specificity of the inhibitory activity by the active-site mapping method. The models can explain the relative enzyme spectra of APPI and BPTI.

Three-dimensional structure of protein C inhibitor predicted from structure of alpha 1-antitrypsin with computer graphics.

The three-dimensional structure of a proteolytically modified protein C inhibitor, a member of the serine protease inhibitor superfamily, was constructed with computer graphics based on its amino acid sequence homology with that of the modified alpha 1-antitrypsin whose structure had been elucidated by X-ray crystallography. The intact form of protein C inhibitor was predicted with an alpha-carbon model based on its hydrophilicity and hydrogen bond pattern. Furthermore, a model of its interaction with activated protein C was constructed based on the structure of the complex between trypsin and its inhibitor, which had been determined by X-ray crystallography.

Protective role of IgA1 glycans against IgA1 self-aggregation and adhesion to extracellular matrix proteins.

The aim of this study was to investigate the role of carbohydrate moieties attached to IgA1 hinge region in IgA1 self-aggregation and adhesion to extracellular matrix (ECM) proteins previously reported in IgA nephropathy. Serum IgA1 samples isolated from healthy individuals were digested with neuraminidase (NA), NA + beta-galactosidase, and NA + beta-galactosidase + alpha-N-acetylgalactosaminidase to remove the carbohydrates from the hinge region and were named asialo, agalacto, and naked IgA1, respectively. First, polyacrylamide gel electrophoresis was performed under the native condition, and consequently, a broad band indicating IgA1 self-aggregation was clearly observed in asialo, agalacto, and naked IgA1, but not in native IgA1. However, the broad band disappeared in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under the nonreducing condition. Second, it was shown that IgA1 adhesion activities to type IV collagen, fibronectin, and laminin were significantly higher in asialo, agalacto, and naked IgA1 than in native IgA1, using enzyme-linked immunosorbent assay (asialo, agalacto, and naked versus native: P < 0.01). In addition, agalacto IgA1 had the highest affinity for all of the ECM proteins among the deglycosylated IgA1 (agalacto versus asialo and naked, P < 0.05). These results indicated that the removal of carbohydrates from the IgA1 molecule resulted in noncovalent self-aggregation and a significant increase in adhesion to the ECM proteins. It was therefore suggested that the IgA1 glycans played a protective role against aggregation and adhesion and that the underglycosylation of the IgA1 molecule found in IgA nephropathy could be involved in the nonimmunologic glomerular accumulation of IgA1.

Evidence for a site-specific fucosylation of N-linked oligosaccharide of immunoglobulin A1 from normal human serum.

Glycopeptides containing the N-linked oligosaccharide from human serum IgA1 were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). Two glycopeptides, GP1 and GP2, prepared from the endoproteinase Asp-N digest of the IgA1 heavy chain, were derived from the CH2 domain (N-glycan site at Asn263) and the tailpiece portion (N-glycan site at Asn459), respectively. The structure of the attached sugar chain was deduced from the mass number of the glycopeptide and confirmed by a two-dimensional mapping technique for a pyridylaminated oligosaccharide. GP1 was composed of two major components having a fully galactosylated bianntena sugar chain with or without a bisecting N-acetylglucosamine (GlcNAc) residue. On the other hand, the GP2 fraction corresponded to the glycopeptides having a fully galactosylated and fucosylated bianntena sugar chain partly bearing a bisecting GlcNAc residue. Thus, the site-specific fucosylation of the N-linked oligosaccharide on the tailpiece of the alpha1 chain became evident for normal human serum IgA1.

Underglycosylation of IgA1 hinge plays a certain role for its glomerular deposition in IgA nephropathy.

This study was performed to isolate and investigate the IgA1 that could accumulate in glomeruli (glomerulophilic IgA1). IgA1 was fractionated by the electric charge and the reactivity to Jacalin. Serum IgA1 of IgA nephropathy patients was separated and fractionated using a Jacalin column and subsequent ion-exchange chromatography. The fractions were divided into three groups of relatively cationic (C), neutral (N), and anionic (A). IgA1 was also divided into Jacalin low (L), intermediate (I), and high (H) affinity fractions by serial elution using 25, 100, and 800 mM galactose. The left kidneys of Wistar rats were perfused with 2, 5, or 10 mg of each group of IgA1. The rats were sacrificed 15 min, 30 min, 3 h, or 24 h after the perfusion. The accumulation of each IgA1 in the glomeruli was then observed by immunofluorescence. The IgA1 of the fractions N and H separated by the two methods was definitely accumulated in the rat glomeruli with a similar pattern. The electrophoresis revealed that the macromolecular IgA1 was increased in fraction H compared with other fractions. Therefore, Jacalin high-affinity IgA1(fraction H) was applied on a diethylaminoethyl column and divided into electrically cationic (HC), neutral (HN), and anionic (HA). Only the asialo-Galbeta1,3GalNAc chain was identified in the fraction HN IgA1 by gas-phase hydrazinolysis. Furthermore, the IgA1 fraction was strongly recognized by peanut agglutinin, Vicia Villosa lectins, and antisynthetic hinge peptide antibody. These results indicated that the IgA1 molecules having the underglycosylated hinge glycopeptide played a certain role in the glomerular accumulation of IgA1 in IgA nephropathy.

Participation of the left posterior inferior temporal cortex in writing and mental recall of kanji orthography: A functional MRI study.

To examine the neuropsychological mechanisms involved in writing kanji (morphograms), we used functional MRI (fMRI) in 10 normal volunteers, all right-handed, native Japanese speakers. The experimental paradigms consisted of kana-to-kanji transcription, mental recall of kanji orthography and oral reading and semantic judgement of kana words. The first two tasks require manual and mental transcription of visually presented kana words into kanji, respectively, whereas the last two tasks involve language processing of the same set of stimulus words without recall of kanji. The transcription and mental recall tasks yielded lateralized activation of the left posterior inferior temporal cortex (PITC). By contrast, neither oral reading nor semantic judgement produced similar activation of the area. These results, in good accordance with lesion data, provide converging evidence that the left PITC plays an important role in writing kanji through retrieval of their visual graphic images, and suggest language-specific cerebral organization of writing. The set of fMRI experiments also provides new neuroimaging data on the cortical localization of basic language functions in people using a non-alphabetical language.