Quantitative description of the slowly inactivated barium current through the somatic membrane of molluscan neurons

The potential-dependent slowly inactivated barium current through the somatic membrane of identified neurons of the molluskHelix pomatia was investigated under voltage clamp conditions. The experimental data were analyzed by the equations of Hodgkin and Huxley. Steady-state values of the inactivation variable of this current were shown to be a function, described approximately by an analytical equation, of membrane potential. The slowly inactivated barium current was shown to be proportional to the third power of the activation variable. The dependence of the time constant of activation of this current on membrane potentials was investigated.     

A quantitative description of membrane current and its application to conduction and excitation in nerve

This article concludes a series of papers concerned with the flow of electric current through the surface membrane of a giant nerve fibre (Hodgkinet al., 1952,J. Physiol. 116, 424–448; Hodgkin and Huxley, 1952,J. Physiol. 116, 449–566). Its general object is to discuss the results of the preceding papers (Section 1), to put them into mathematical form (Section 2) and to show that they will account for conduction and excitation in quantitative terms (Sections 3–6).     

玉米冠层的数学描述与三维重建研究

采用Lang提出的原理开发了空间坐标仪。利用该仪器测定玉米冠层的空间坐标,以此提出了应用一般二次方程描述玉米叶曲线和叶形的数学方法,方程的系数由最小二乘回归方法得到,其中叶曲线系数由叶片主脉坐标决定,叶形系数由沿叶长方向叶宽测定值决定。从而使应用较少参数描述真实的玉米群体结构成为可能。另外,还实现了玉米冠层的计算机三维重建,为农业生态系统研究提供了新的手段。     

Alteration by xylocaine (lidocaine) and its derivatives of the time course of the end plate potential

Xylocaine and its derivatives act specifically at the neuromuscular junction within the concentration range 0.05 to 2.0 mM. The charged form is the active form of the drugs. There is no correlation between "local anesthetic" activity and effect at the junction. Like d-tubocurarine, these drugs have little or no effect on quantum content, acetylcholinesterase activity, or the passive impedance of the muscle fiber. Yet they produce end plate potentials characterized by a brief, early component and a late, greatly prolonged component, as does procaine. Analysis of these changes in time course suggests that the drugs have little or no effect before receptors are activated by acetylcholine, but cause a decreased and often greatly prolonged response. Clear structure-activity relations indicate that the receptor to which the drugs bind to produce the prolonged response can be the receptor for acetylcholine. Comparison of the effects of the drugs on the end plate potential and on the response to iontophoretically applied acetylcholine also shows that the effects of Xylocaine depend on the time course of receptor activation and are quite different from the effects of d-tubocurarine.     

Mesozoic plate tectonic reconstruction of the Carpathian region

Palaeomagnetic, palaeobiogeographic and structural comparisons of different parts of the Alpine-Carpathian region suggest that four terranes comprise this area: the Alcapa, Tisza, Dacia and Adria terranes. These terranes are composed of different Mesozoic continental and oceanic fragments that were each assembled during a complex Late Jurassic-Cretaceous-Palaeogene history. Palaeomagnetic and tectonic data suggest that the Carpathians are built up by two major oroclinal bends. The Alcapa bend has the Meliata oceanic unit, correlated with the Dinaric Vardar ophiolite, in its core. It is composed of the Western Carpathians, Eastern Alps and Southern Alcapa units (Transdanubian Range, Bükk). This terrane finds its continuation in the High Karst margin of the Dinarides. Further elements of the Alcapa terrane are thought to be derived from collided microcontinents: Czorsztyn in the N and a carbonate unit (Tisza?) in the SE. The Tisza-Dacia bend has the Vardar oceanic unit in its core. It is composed of the Bihor and Getic microcontinents. This terrane finds its continuation in the Serbo-Macedonian Massif of the Balkans.The Bihor-Getic microcontinent originally laid east of the Western Carpathians and filled the present Carpathian embayment in the Late Palaeozoic-Early Mesozoic. The Vardar ocean occupied an intermediate position between the Western Carpathian-Austroalpine-Transdanubian-High Karst margin and the Bihor-Getic-Serbo-Macedonian microcontinent. The Vardar and Pindos oceans were opened in the heart of the Mediterranean-Adriatic microcontinent in the Late Permian-Middle Triassic. Vardar subducted by the end of Jurassic, causing the Bihor-Getic-Serbo-Macedonian microcontinent to collide with the internal Dinaric-Western Carpathian margin.An external Penninic-Váhic ocean tract began opening in the Early Jurassic, separating the Austroalpine-Western Carpathian microcontinent (and its fauna) from the European shelf. Further east, the Severin-Ceahlau-Magura also began opening in the Early Jurassic, but final separation of the Bihor-Getic ribbon (and its fauna) from the European shelf did not take place until the late Middle Jurassic.The Alcapa and the Tisza-Dacia were bending during the Albian-Maastrichtian. The two oroclinal bends were finally opposed and pushed into the gates of the Carpathian embayment during the Palaeogene and Neogene. At that time, the main N-S shortening in distant Alpine and Hellenic sectors was linked by a broader right-lateral shear zone along the former Vardar suture.     

Histochemical localization of folic acid in the motor end plate

Folic acid investigated in motor end plate by histochemical method appeared in the long nerve terminals of the motor axon, in the cytoplasm of Schwann cell. In muscle fibre opposite to the nerve arborizations, spaced granular lines perpendicular to the sarcolemma were observed.     

Results and current approach for Brachial Plexus reconstruction

We review our experience treating 335 adult patients with supraclavicular brachial plexus injuries over a 7-year period at the University of Southern Santa Catarina, in Brazil. Patients were categorized into 8 groups, according to functional deficits and roots injured: C5-C6, C5-C7, C5-C8 (T1 Hand), C5-T1 (T2 Hand), C8-T1, C7-T1, C6-T1, and total palsy. To restore function, nerve grafts, nerve transfers, and tendon and muscle transfers were employed. Patients with either upper- or lower-type partial injuries experienced considerable functional return. In total palsies, if a root was available for grafting, 90% of patients had elbow flexion restored, whereas this rate dropped to 50% if no roots were grafted and only nerve transfers performed. Pain resolution should be the first priority, and root exploration and grafting helped to decrease or eliminate pain complaints within a short time of surgery.     

Changes in interspike interval during propagation: Quantitative description

The intervals between nerve impulses can change substantially during propagation because of conduction velocity aftereffects of previous impulse activity. Effects of such changes on interval histograms and on statistical parameters of spike trains were evaluated for Poisson spike trains and for trains generated by a clock with added random delays. The distribution of short intervals was significantly changed during propagation for these spike trains. Substantial changes in serial correlation coefficients were found in trains with certain initial interval distributions. The relevance of these effects to neural coding is discussed.     

Quantitative description and discrimination of butterfly wing patterns using moment invariant analysis

Studies examining and using pattern variation in insects for identification and characterization of individuals and populations have been limited by the methods available for quantifying wing patterns objectively. In this paper, differences in wing pattern are demonstrated statistically using moment invariant data sets generated automatically from digitized images of the speckled wood butterfly, Pararge aegeria (Linnaeus). Studies with other biological subjects have already shown moment invariants to work well with outline shapes and silhouettes. A pilot study with replicated monochrome photographs of a single butterfly showed the method could detect pattern differences between wing surfaces, even in the presence of simulated wing fading and damage. In a further study of the wings of 228 specimens, multivariate analyses of variance using the moment data reliably detected differences between groups of butterflies according to sex, geographical origin and culture history. Potential applications and future improvements of the moment methodology are considered.     

Habitat monitoring in Europe: a description of current practices

Monitoring of biodiversity at the level of habitats is becoming increasingly common. Here we describe current practices in habitat monitoring based on 150 schemes in Europe. Most schemes were initiated after 1990 in response to EU nature directives or habitat management/restoration actions, with funding mostly from European or national sources. Schemes usually monitor both the spatial distribution and the quality of the habitats, and they frequently collect data on environmental parameters and potential causes of changes. Many schemes are local or regional rather than national or international in scope, and sampling effort varies greatly across spatial and temporal scales. Experimental design is used in half of the schemes, however, data are rarely analysed by advanced statistics. Most schemes require two months or less per year in manpower and are typically run by professionals rather than by volunteers. Estimated salaries plus equipment costs average 650,000 Euro per year per scheme, and add up to 80 million Euros annually. Costs are particularly high for schemes based on European or international law and for schemes funded by European or national sources. Costs are also high in schemes in which sampling sites are selected subjectively rather than based on sampling theory, and in schemes that do not use field mapping or remote sensing to document spatial variation in habitats. Our survey demonstrates promising developments in European habitat monitoring but also underlines the need for better spatial coverage, documentation of spatial variaton, improved sampling design and advanced data analysis. Such improvements are essential if we are to judge progress towards the 2010 biodiversity targets.     

Quantitative reconstruction of leukocyte subsets using DNA methylation

Background

Cell lineage-specific DNA methylation patterns distinguish normal human leukocyte subsets and can be used to detect and quantify these subsets in peripheral blood. We have developed an approach that uses DNA methylation to simultaneously quantify multiple leukocyte subsets, enabling investigation of immune modulations in virtually any blood sample including archived samples previously precluded from such analysis. Here we assess the performance characteristics and validity of this approach.

Results

Using Illumina Infinium HumanMethylation27 and VeraCode GoldenGate Methylation Assay microarrays, we measure DNA methylation in leukocyte subsets purified from human whole blood and identify cell lineage-specific DNA methylation signatures that distinguish human T cells, B cells, NK cells, monocytes, eosinophils, basophils and neutrophils. We employ a bioinformatics-based approach to quantify these cell types in complex mixtures, including whole blood, using DNA methylation at as few as 20 CpG loci. A reconstruction experiment confirms that the approach could accurately measure the composition of mixtures of human blood leukocyte subsets. Applying the DNA methylation-based approach to quantify the cellular components of human whole blood, we verify its accuracy by direct comparison to gold standard immune quantification methods that utilize physical, optical and proteomic characteristics of the cells. We also demonstrate that the approach is not affected by storage of blood samples, even under conditions prohibiting the use of gold standard methods.

Conclusions

Cell mixture distributions within peripheral blood can be assessed accurately and reliably using DNA methylation. Thus, precise immune cell differential estimates can be reconstructed using only DNA rather than whole cells.