Non-mediated zero voltage conductance of hydrophobic ions through bilayer lipid membranes

A charge pulse technique applied to the study of charge transfer at metal-solution interfaces has been used to determine the capacity and the conductance of a membrane bilayer at both zero time and zero voltage. The transport of hydrophobic ion across a glycerol-monooleate bilayer (tetraphenyl borate, picrate, dipicrylamine and tetraphenyl arsonium) has been investigated by this method. A theoretical approach to the problem has been proposed based on one analogous to that used for the compact double layer at metallic electrodes.     

Non-mediated zero voltage conductance of hydrophobic ions through bilayer lipid membranes.

A charge pulse technique applied to the study of charge transfer at metal-solution interfaces has been used to determine the capacity and the conductance of a membrane bilayer at both zero time and zero voltage. The transport of hydrophobic ions across a glycerol-monooleate bilayer (tetraphenyl borate, picrate, dipicrylamine and tetraphenyl arsonium) has been investigated by this method. A theoretical approach to the problem has been proposed based on one analogous to that used for the compact double layer at metallic electrodes.     

Simultaneous determination of specific antigen, antibody and immune complexes in the serum of patients with chronic schistosomiasis

The main steps of a sensitive and quantitative technique for the simultaneous determination, in the same microplate, of antigen, antibody and specific immune complexes has been described. The assay involved principles of the double sandwich technique used in the "Enzyme-Linked Immunosorbent Assay" (ELISA). The technique proved to be useful for the estimation of antigen, antibody and specific immune complexes in sera of patients with human chronic hepato-intestinal schistosomiasis.     

The linear PCR reaction: a simple and robust method for sequencing amplified rRNA genes

The linear polymerase chain reaction was used to sequence amplified RNA genes from strains of Bacillus, Thermus and Legionella. The technique described is simple and reproducible and it works well with double standard product which has been PEG precipitated directly from PCR reactions.     

Evaluation of double violet agar in the isolation of Klebsiella pneumoniae from river water.

A field evaluation of double violet agar for the isolation and presumptive identification of Klebsiella pneumoniae from water has been performed. Water from the North Oconee River, Clarke County, Ga., was cultured for presence of klebsiellae using the membrane filter technique. Colonies were presumptively identified as K. pneumoniae in the basis of their appearance on double violet agar. Such identifications were evaluated using appropriate biochemical tests. Once investigators have become familiar with cultural reactions on the medium, double violet agar can be used to indicate presence of K. pneumoniae in water with greater than 80% accuracy.     

An alkaline-phosphatase staining method in avidin-biotin immunohistochemistry

An avidin-biotin alkaline-phosphatase (ABAP) staining method has been developed for the labeling of tissue sections and cell smears. The introduction of alkaline phosphatase as a marker enzyme through an avidin bridge results in excellent immunocytochemical labeling of different antigens using poly- and monoclonal antibodies. This technique avoids problems with endogenous peroxidase activity that sometimes occur using peroxidase staining procedures. The introduction of a preformed avidin-biotin alkaline-phosphatase complex (ABAPC) makes the presented technique as simple to handle as the widely used avidin biotin-peroxidase complex method (ABC). The ABAPC technique could be combined with other enzymatic labelings for double immunoenzymatic staining.     

Morphology of the meniscotemporal part of the temporomandibular joint and its biomechanical implications

The temporomandibular joint is a diarthrosis. It has classically been referred to as being a condylar, and functionally as a double condylar joint. We have used the moiré topographical technique to study the morphology of the pars suprameniscalis or meniscotemporalis of the joint. The findings show that this pars suprameniscalis could be classified as a saddle joint. The biomechanical implications are also discussed.     

Use of a radioimmunoassay technique to measure the titer of anti-cow-zona antibodies in marmoset monkeys

A double antibody radioimmunoassay technique is described for the measurement of anti-zona antibodies in the peripheral plasma of marmosets actively immunized against intact cow zonae pellucidae. The method has been shown to be a reliable, repeatable indicator of antibody titer, enabling direct comparison of the response obtained between marmosets. This is the first report of a procedure describing the active immunization of a primate against zona antigens, and the first time a radioimmunoassay technique has been used to monitor profiles of anti-cow zona antibody production following active immunization. The method should prove to be a useful tool in the evaluation of zona antigens as agents for immunocontraception.     

Localized vibrational modes at a double-helix-single-strand junction

A vibrational analysis has been performed for a double-helix–single-strand junction. A Green's function technique has been used in treating the junction as a defect on an otherwise perfect system of infinite chain homopolymers. We calculate that the hydrogen-bond stretching at the junction is amplified by a factor of two relative to the interior of the double helix, B poly(dG)–poly(dC). Breathing modes localized near the junction have also been predicted at 77 and 94 wave numbers. The calculated results are shown to be consistent with predictions from recent nmr studies.     

Dual-colour imaging with GFP variants

Green fluorescent protein (GFP) has become an important tool in cell biology and is widely used as a reporter for imaging intracellular proteins and structures in live cells. Recently, spectral variants of GFP with red- and blue-shifted fluorescence emissions have been characterized, opening the possibility of double labelling with two different-coloured GFP fusion proteins. This article reviews recent advances in this technique, with special emphasis on time-lapse imaging applications in living cells.     

Dust ion acoustic solitary structures in the presence of isothermal positrons

The Sagdeev potential technique has been employed to study the dust ion acoustic solitary waves and double layers in an unmagnetized collisionless dusty plasma consisting of negatively charged static dust grains, adiabatic warm ions, isothermally distributed electrons, and positrons. A computational scheme has been developed to draw the qualitatively different compositional parameter spaces or existence domains showing the nature of existence of different solitary structures with respect to any parameter of the present plasma system. The present system supports both positive and negative potential double layers. The negative potential double layer always restricts the occurrence of negative potential solitary waves, i.e., any sequence of negative potential solitary waves having monotonically increasing amplitude converges to a negative potential double layer. However, there exists a parameter regime for which the positive potential double layer is unable to restrict the occurrence of positive potential solitary waves. As a result, in this region of the parameter space, there exist solitary waves after the formation of positive potential double layer, i.e., positive potential supersolitons have been observed.     

Identification of the soluble HVP-associated antigen of the lymphoblastoid cell line established from lymphomatous baboon (Papio hamadryas).

A new technique (indirect double immunodiffusion) for detection of EBV-associated soluble antigen and corresponding antibodies has been developed. This technique includes three steps: 1) simple double immunodiffusion with extracts of Raji cells (or other EBV-genome positive cells) and human sera containing antibodies against EBV-associated soluble antigen; 2) extensive washing and treatment with anti-human globulin; 3) extensive washing and treatment with tannic acid. Using this test it was shown that the soluble antigen indistinguishable from EBV-associated soluble antigen was present in KMPG-1 cells producing HVP.     

The reaction of unsaturated fats with the acid hematein test

Summary The reaction of saturated and unsaturated oils and fatty acids was examined in vitro with the Baker's acid hematein test. It has been found that oils whose molecules contain fatty acid components of two or more double bonds give a positive reaction with the acid hematein technique. The intensity of the reaction runs parallel with the number of double bonds.     

The margin for error when releasing the asymmetric bars for dismounts

It has previously been shown that male gymnasts using the "scooped" giant circling technique were able to flatten the path followed by their mass center, resulting in a larger margin for error when releasing the high bar (Hiley and Yeadon, 2003a). The circling technique prior to performing double layout somersault dismounts from the asymmetric bars in women's artistic gymnastics appears to be similar to the "traditional" technique used by some male gymnasts on the high bar. It was speculated that as a result the female gymnasts would have margins for error similar to those of male gymnasts who use the traditional technique. However, it is unclear how the technique of the female gymnasts is affected by the need to avoid the lower bar. A 4-segment planar simulation model of the gymnast and upper bar was used to determine the margins for error when releasing the bar for 9 double layout somersault dismounts at the Sydney 2000 Olympics. The elastic properties of the gymnast and bar were modeled using damped linear springs. Model parameters, primarily the inertia and spring parameters, were optimized to obtain a close match between simulated and actual performances in terms of rotation angle (1.2 degrees), bar displacement (0.011 m), and release velocities (<1%). Each matching simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the dismount successfully. The margins for error of the 9 female gymnasts (release window 43-102 ms) were comparable to those of the 3 male gymnasts using the traditional technique (release window 79-84 ms).     

锌指核酸酶技术的应用

锌指核酸酶(zinc finger nuclease,ZFN)技术是近年来发展起来的一种对基因组DNA实现靶向修饰的新技术。ZFN通过作用于基因组DNA上特异的靶位点产生DNA双链切口(double strand break,DSB),然后经过非同源末端连接(non-homologous end joining,NHEJ)或同源重组(homologous recombination,HR)途径实现对基因组DNA的靶向敲除或者替换。该技术近些年来已经被广泛应用于基因靶向修饰的研究。本文在简要介绍ZFN技术的基础上,重点综述了目前该技术在基因靶向修饰中的应用研究进展,并同时对该技术目前所需解决的一些问题以及未来的研究方向进行了分析。     

Solid phase DNA sequencing using the biotin-avidin system.

A novel method for solid-phase DNA sequencing is described. A plasmid vector, pRIT27, has been designed to allow directional immobilization of double stranded plasmid to avidin agarose. The strategy involves enzymatic incorporation of 11-bio-dUTP into the plasmid and strand specific elution using alkali. The immobilized single stranded DNA is used as template for sequencing reactions and the resulting labelled oligonucleotides are eluted by alkali. The affinity gel containing the immobilized template is consecutively used for the four different dideoxy-nucleotide reactions. The solid-phase technique can be used for both primer specific or extension specific labelling. The possibility to use the system in automated DNA sequencing is discussed.     

Application of 13C nuclear magnetic resonance spectroscopy to molecular structural analyses of antibody molecules

A 13C nuclear magnetic resonance study of a mouse anti-dansyl monoclonal antibody is reported. The antibody molecule was specifically labeled with [1-13C]methionine by growing hybridoma cells in serum-free medium. It was possible to observe all the carbonyl carbon resonances of the antibody. Fab and Fc fragments have been obtained from the antibody and used successfully for the assignment of each of the carbonyl resonances to either the Fab or Fc region. It has been shown that the spectrum of the intact antibody is simply those of Fab and Fc superimposed. It has also been shown that site specific assignments of carbonyl resonances can be made by means of a double labeling technique developed by Kainosho and coworkers.     

Post-embedding double-labeling of antigen-retrieved ultrathin sections using a silver enhancement-controlled sequential immunogold (SECSI) technique.

In electron microscopy, the post-embedding immunogold technique provides a high degree of resolution and the possibility of quantitation owing to the intrinsic characteristics of the colloidal gold marker. Application of this technique to the subcellular localization of multiple antigens by differential labeling using gold markers of different sizes, or to double labeling using the same primary antibody isotype with serial silver enhancement, has been reported. We have incorporated this double labeling technique into a modified procedure that produces excellent labeling and ultrastructural preservation, even after exposure of ultrathin sections large enough to cover a 300- micro m-diameter single-hole grid to hot antigen retrieval solutions and prolonged labeling protocols.     

Brachioplasty technique with the use of molds

Over previous years many surgical techniques have been developed to correct lipodystrophy and brachial skin laxity while providing a natural, discreet contour and symmetrical scars, a goal that has not always been achieved. In this study, the authors classify the alterations of the arm into three degrees and propose a different surgical treatment, to be used alone or associated with another procedure, for each classification. They developed a new technique that uses a mold to mark the incision in an italic double S-shape. From 1996 to 1998, 20 patients who underwent this surgery showed symmetrical and smaller scars with better results and minimal complications.     

Behavior of the chromosome core in mitosis and meiosis

A simple method has been described for the visualization of chromosome cores with light microscopy in conventional chromosome preparations. The technique is relatively simple, highly reproducible and can be used effectively on fresh and aged slides. The following observations have been made: (1) a core existed in mitotic chromosomes in all the materials employed, confirming the findings of Howell and Hsu (1979). (2) The microchromosomes of the chicken and double minutes of a human carcinoma cell line also exhibited the core structure. (3) The core structure of meiotic chromosomes appear weak, disorganized, and disintegrating.