Determination of the Pressure Drop Across an Arterial Stenosis Utilizing Angiocinedensitometry

A method is presented for an evaluation of the hemodynamic significance of a stenotic lesion in the arterial tree.Twenty-three patients were examined with arteriosclerosis obliterans and intermittent claudication of the same severity. Flow velocity data obtained by angiodensitometry and viscosity values calculated from the hematocrit were inserted into the Poiseuille''s flow formula to obtain the pressure drop across a stenotic lesion in the left external iliac artery. By the same way, the pressure gradient was calculated in 33 “normal” subjects.The normal pressure gradient along the external iliac artery varied between 23 to 110 dynes/cm² (52 ± 24 dynes/cm² for mean and S.d), and the normal resistance to flow was 6.08 ± 4.1 dyne sec/cm⁵).Stenotic lesions of similar dimensions gave widely varying pressure drops (114-4,736 dynes/cm²) (mean and S.d 1,309 ± 1,224 dynes/cm²) indicating a difference in the hemodynamic significance of the various lesions. These values were significantly different (p(t) < 0.001) from the normal values. The resistance across these stenotic lesions ranged between 21 to 768 dyne sec/cm⁵ (196 ± 192 dyne sec/cm⁵) for the mean and S.d and this was significantly different from the normal group; p(t) < 0.001.Direct measurement of blood viscosity coupled with angiocinedensitometry at rest and after forced vasodilatation should provide an accurate means of determining the relative significance of a stenotic lesion and distal vessel disease in a given patient on blood flow to the leg.     

A Double-Taper Optical Fiber-Based Radiation Wave Other than Evanescent Wave in All-Fiber Immunofluorescence Biosensor for Quantitative Detection of Escherichia coli O157:H7

Cylindrical or taper-and-cylinder combination optical fiber probe based on evanescent wave has been widely used for immunofluorescence biosensor to detect various analytes. In this study, in contrast to the contradiction between penetration depth and analyte diameter of optical fiber probe-based evanescent wave, we demonstrate that double-taper optical fiber used in a radiation wave-based all-fiber immunofluorescence biosensor (RWAIB) can detect micron-scale analytes using Escherichia coli O157:H7 as representative target. Finite-difference time-domain method was used to compare the properties of evanescent wave and radiation wave (RW). Ray-tracing model was formulated to optimize the taper geometry of the probe. Based on a commercial multi-mode fiber, a double-taper probe was fabricated and connected with biosensor through a “ferrule connector” optical fiber connector. The RWAIB configuration was accomplished using commercial multi-mode fibers and fiber-based devices according to the “all-fiber” method. The standard sample tests revealed that the sensitivity of the proposed technique for E. coli O157:H7 detection was 10³ cfu·mL⁻¹. Quantitation could be achieved within the concentration range of 10³ cfu·mL⁻¹ to 10⁷ cfu·mL⁻¹. No non-specific recognition to ten kinds of food-borne pathogens was observed. The results demonstrated that based on the double-taper optical fiber RWAIB can be used for the quantitative detection of micron-scale targets, and RW sensing is an alternative for traditional evanescent wave sensing during the fabrication of fiber-optic biosensors.     

Elastic Properties of the Sea Urchin Sperm Flagellum

The theory of flexural vibrations in thin rods, applied to the movement of flagella, has been extended to include an investigation of the influence of the boundary conditions on the theoretical waveforms. It was found that for flagella which are flexible enough, the flexibility can be estimated solely from the wavelength of the wave traveling in it. This can be expected to hold for those flagella which do not possess a fibrous sheath. The bending moment in flagella in which the ampitude of the wave is maintained as the wave travels distally is almost completely produced by active contractile elements. This means that the active bending moment can be estimated from the radius of curvature of the flagellum and the stiffness. The above findings were applied to the case of the sea urchin sperm flagellum. One finds that the stiffness of the flagellum is caused mainly by the nine longitudinal fibers which must have a Young's modulus of slightly less than 10⁸dyne/cm². The longitudinal fibers need to develop a tension of 1.6 × 10⁸dyne/cm² to account for the bending moment in the flagellum. These two figures are in line with those found for muscle fibers.     

Dominating Role of an Unusual Magnetotactic Bacterium in the Microaerobic Zone of a Freshwater Sediment

A combination of polymerase chain reaction-assisted rRNA sequence retrieval and fluorescent oligonucleotide probing was used to identify in situ a hitherto unculturable, big, magnetotactic, rod-shaped organism in freshwater sediment samples collected from Lake Chiemsee. Tentatively named “Magnetobacterium bavaricum,” this bacterium is evolutionarily distant from all other phylogenetically characterized magnetotactic bacteria and contains unusually high numbers of magnetosomes (up to 1,000 magnetosomes per cell). The spatial distribution in the sediment was studied, and up to 7 × 10⁵ active cells per cm³ were found in the microaerobic zone. Considering its average volume (25.8 ± 4.1 μm³) and relative abundance (0.64 ± 0.17%), “M. bavaricum” may account for approximately 30% of the microbial biovolume and may therefore be a dominant fraction of the microbial community in this layer. Its microhabitat and its high content of sulfur globules and magnetosomes suggest that this organism has an iron-dependent way of energy conservation which depends on balanced gradients of oxygen and sulfide.     

Simultaneous Measurement of NH(4) Absorption and N(2) Fixation by Glycine max L. : RESPONSE TO TEMPERATURE, pH, AND EXTERNAL NITROGEN CONCENTRATION

Curvature, bending moment, and second moment of stem cross-sectional area were evaluated from photographic data and used to compute flexural rigidity and Young's modulus in the panicle rachis of rice, Oryza sativa L. `M-101.' Flexural rigidity C, and its components E, Young's modulus, and I, the moment of inertia of the area about the neutral axis, were evaluated 1.5 cm (tip), 9.5 cm (mid), and 16.5 cm (base) from the tip of the panicle rachis. In dynes per square centimeter, C increases from 1.1 × 10³ near the tip to 1.09 × 10⁴ in the middle to 5.35 × 10⁴ in the basal region of the rachis. Of the components of C, the I changes have the larger effect, increasing from 2.12 × 10⁻⁷ centimeters⁴ near the tip to 8.21 × 10⁻⁷ centimeters⁴ in mid regions to 6.0 × 10⁻⁶ centimeters⁴ in the basal regions. Young's modulus increases from 4.8 × 10⁹ dynes per square centimeter near the tip to 1.4 × 10¹⁰ dynes per square centimeter in mid regions then falls to 7.4 × 10⁹ dynes per square centimeter near the base of the main stem. Values of Young's modulus from Instron experiments were in satisfactory agreement with values calculated from the beam bending equation. Flexural rigidity in the curved region of the panicle proved independent of panicle load, indicating that the dissected panicle rachis behaves in some respects as a tapered loaded beam.     

Some Peculiarities of Water Transport through Plasticized Nonporous Membranes

“Liquid” and “plasticized” solvent membranes are of interest as possible analogues of biological systems. Semipermeable homogeneous films are prepared by plasticizing polyvinylchloride with organic phosphates. Water permeability of such films is relatively high. For a material containing 70% of 1.4-dihydroxyphenyl-bis(dibutylphosphate), the diffusion coefficient of water at room temperature was estimated to be about 1 × 10^-6 cm²/sec. Conditioning of a plasticized membrane, under the osmotic gradient of solution of sodium nitrate, leads to profound changes in its morphology and to a drastic increase of its water permeability. The induced changes are reversible to a large extent. Their reversibility in various solutions may be correlated with the respective differences in permselectivity. The structure of expanded membranes and the mechanism of changes taking place under the osmotic gradients are discussed.     

White light requirements for stimulation of plant growth by malformin

Over a 3-day period, the minimum white fluorescent light intensity required for malformin-induced growth stimulation of etiolated and green cuttings of Phaseolus aureus was approximately 2.6 × 10³ and 0.4 × 10³ ergs/cm² · sec, respectively. High light intensities were unable to inhibit the ability of malformin to stimulate growth. Over 3 days, the minimum photoperiod for malformin-induced growth stimulation using etiolated and green cuttings and a light intensity of 13.5 × 10³ ergs/cm² · sec was 4 hours and 1 hour, respectively. Malformin must be present in the area of growth stimulation during the time of light treatment. Those changes induced by light and required for malformin-induced growth stimulation were estimated to undergo almost complete decay within 1 hour in the dark. By manipulating the experimental technique, it was possible to stimulate the growth of green cuttings with malformin with a 10-min light treatment (13.5 × 10³ ergs/cm² · sec). Although low light intensities and short photoperiods did not allow growth stimulation by malformin using etiolated cuttings, they prevented or alleviated growth inhibition induced by malformin in the dark.     

Hydration effects of Ni(2+) binding to synthetic polynucleotides with regularly alternating purine-pyrimidine sequences

High precision ultrasonic and densimetric techniques have been used to study the interaction of Ni²⁺ ions with right-handed poly[d(G-C)]·poly[d(G-C)], poly-[d(A-C)]·poly[d(G-T)] and poly[d(A-T)]·poly[d(A-T)] in 5 mM CsCl, 0.2 mM HEPES, pH 7.5 at 20°C. From these measurements the changes in the apparent molar volume and the apparent molar adiabatic compressibility due to the interaction have been obtained. The volume effects of the binding, calculated per mole of Ni²⁺ ions, range from 11.7 to 23.9 cm³ mol^–1 and the compressibility effects range from 19.3 × 10^–4 to 43.1 × 10^–4 cm³ mol^–1 bar^–1. These data are interpreted in terms of dehydration of the polynucleotides and Ni²⁺ ions, i.e. the release of water molecules from the hydration shells of the molecules. An increase in G+C content gives an increase in volume and compressibility effects, indicating a rise in the extent of dehydration. The dehydration effects of Ni²⁺ binding to poly[d(G-C)]·poly[d(G-C)] are approximately twice those of poly[d(A-T)]·poly[d(A-T)]. The volume and compressibility effects of Ni²⁺–EDTA complex formation have also been measured and used as a model system for quantitative estimation. These values revealed that Ni²⁺ ions can coordinate two atomic groups of poly[d(G-C)]·poly[d(G-C)], while in the case of the Ni²⁺–poly[d(A-T)]·poly[d(A-T)] complex volume and compressibility effects correspond to one direct or two indirect (through water) contacts.     

Rho Kinases Regulate the Renewal and Neural Differentiation of Embryonic Stem Cells in a Cell Plating Density–Dependent Manner

Background

Rho kinases (ROCKs) mediate cell contraction, local adhesion, and cell motility, which are considered to be important in cell differentiation. We postulated that ROCKs are involved in controlling embryonic stem (ES) cell renewal and differentiation.

Methodology/Principal Findings

CCE, a murine ES cell, was treated with Y-27632 for 48 to 96 hours and colony formation was evaluated. Y-27632 blocked CCE colony formation and induced CCE to grow as individual cells, regardless of the initial seeding cell density either at 10⁴/cm² (“high” seeding density) or 2×10³/cm² (“low” density). However, at high seeding density, Y-27632–treated cells exhibited reduction of alkaline phosphatase (AP) staining and Oct3/4 expression. They expressed SOX-1, nestin, and MAP2c, but not βIII-tubulin or NG-2. They did not express endoderm or mesoderm lineage markers. After removal of Y-27632, the cells failed to form colonies or regain undifferentiated state. Silencing of ROCK-1 or ROCK-2 with selective small interference RNA induced CCE morphological changes similar to Y-27632. Silencing of ROCK-1 or ROCK-2 individually was sufficient to cause reduction of AP and Oct3/4, and expression of SOX-1, nestin, and MAP2c; and combined silencing of both ROCKs did not augment the effects exerted by individual ROCK siRNA. Y-27632–treated CCE cells seeded at 2×10³ or 6.6×10³ cells/cm² did not lose renewal factors or express differentiation markers. Furthermore, they were able to form AP-positive colonies after removal of Y-27632 and reseeding. Similar to ROCK inhibition by Y-27632, silencing of ROCK-1 or ROCK-2 in cells seeded at 2×10³/cm² did not change renewal factors.

Conclusions/Significance

We conclude that ROCKs promote ES cell colony formation, maintain them at undifferentiated state, and prevent them from neural differentiation at high seeding density. ROCK inhibition represents a new strategy for preparing large numbers of neural progenitor cells.     

Morphology,Classification, and Distribution of the Projection Neurons in the Dorsal Lateral Geniculate Nucleus of the Rat

The morphology of confirmed projection neurons in the dorsal lateral geniculate nucleus (dLGN) of the rat was examined by filling these cells retrogradely with biotinylated dextran amine (BDA) injected into the visual cortex. BDA-labeled projection neurons varied widely in the shape and size of their cell somas, with mean cross-sectional areas ranging from 60–340 µm². Labeled projection neurons supported 7–55 dendrites that spanned up to 300 µm in length and formed dendritic arbors with cross-sectional areas of up to 7.0×10⁴ µm². Primary dendrites emerged from cell somas in three broad patterns. In some dLGN projection neurons, primary dendrites arise from the cell soma at two poles spaced approximately 180° apart. In other projection neurons, dendrites emerge principally from one side of the cell soma, while in a third group of projection neurons primary dendrites emerge from the entire perimeter of the cell soma. Based on these three distinct patterns in the distribution of primary dendrites from cell somas, we have grouped dLGN projection neurons into three classes: bipolar cells, basket cells and radial cells, respectively. The appendages seen on dendrites also can be grouped into three classes according to differences in their structure. Short “tufted” appendages arise mainly from the distal branches of dendrites; “spine-like” appendages, fine stalks with ovoid heads, typically are seen along the middle segments of dendrites; and “grape-like” appendages, short stalks that terminate in a cluster of ovoid bulbs, appear most often along the proximal segments of secondary dendrites of neurons with medium or large cell somas. While morphologically diverse dLGN projection neurons are intermingled uniformly throughout the nucleus, the caudal pole of the dLGN contains more small projection neurons of all classes than the rostral pole.     

Broad Distribution of Diverse Anaerobic Ammonium-Oxidizing Bacteria in Chinese Agricultural Soils

Anaerobic ammonium-oxidizing (anammox) bacteria have been detected in many marine and freshwater ecosystems. However, little is known about the distribution, diversity, and abundance of anammox bacteria in terrestrial ecosystems. In this study, anammox bacteria were found to be present in various agricultural soils collected from 32 different locations in China. Phylogenetic analysis of the 16S rRNA genes showed “Candidatus Brocadia,” “Candidatus Kuenenia,” “Candidatus Anammoxoglobus,” and “Candidatus Jettenia” in the collected soils, with “Candidatus Brocadia” being the dominant genus. Quantitative PCR showed that the abundance of anammox bacteria ranged from 6.38 × 10⁴ ± 0.42 × 10⁴ to 3.69 × 10⁶ ± 0.25 × 10⁶ copies per gram of dry weight. Different levels of diversity, composition, and abundance of the anammox bacterial communities were observed, and redundancy analysis indicated that the soil organic content and the distribution of anammox communities were correlated in the soils examined. Furthermore, Pearson correlation analysis showed that the diversity of the anammox bacteria was positively correlated with the soil ammonium content and the organic content, while the anammox bacterial abundance was positively correlated with the soil ammonium content. These results demonstrate the broad distribution of diverse anammox bacteria and its correlation with the soil environmental conditions within an extensive range of Chinese agricultural soils.     

Electroosmosis in Membranes: Effects of Unstirred Layers and Transport Numbers: II. Experimental

In an earlier paper, it was shown that the differences in transport numbers in membranes and adjacent solutions will result in a depletion and enhancement of the local concentration profiles at the appropriate interfaces. These should, in general, cause both current-induced volume flows and transient changes in membrane potential difference (PD). The predicted concentration changes were measured near an isolated segment of plant cell wall just after a current pulse. The current-induced volume flows observed were separated into a “transport number component” and an instantaneous, electroosmotic one for both cell walls and whole cells. For walls, the electroosmotic component contributed about 53 moles · Faraday^-1 to a total coefficient of 112 moles · Faraday^-1. For whole cells, the average electroosmotic component (for both hyperpolarizing and depolarizing currents) contributed about 38 moles · Faraday^-1 to a total of about 100 moles · Faraday^-1. There was good agreement between the magnitudes and time courses of the flows and membrane PD's predicted from the theory in the previous paper, and those measured in both cell walls and whole cells.     

Rotating Magnetic Field-Assisted Reactor Enhances Mechanisms of Phage Adsorption on Bacterial Cell Surface

Growing interest in bacteriophage research and use, especially as an alternative treatment option for multidrug-resistant bacterial infection, requires rapid development of production methods and strengthening of bacteriophage activities. Bacteriophage adsorption to host cells initiates the process of infection. The rotating magnetic field (RMF) is a promising biotechnological method for process intensification, especially for the intensification of micromixing and mass transfer. This study evaluates the use of RMF to enhance the infection process by influencing bacteriophage adsorption rate. The RMF exposition decreased the t₅₀ and t₇₅ of bacteriophages T4 on Escherichia coli cells and vb_SauM_A phages on Staphylococcus aureus cells. The T4 phage adsorption rate increased from 3.13 × 10⁻⁹ mL × min⁻¹ to 1.64 × 10⁻⁸ mL × min⁻¹. The adsorption rate of vb_SauM_A phages exposed to RMF increased from 4.94 × 10⁻⁹ mL × min⁻¹ to 7.34 × 10⁻⁹ mL × min⁻¹. Additionally, the phage T4 zeta potential changed under RMF from −11.1 ± 0.49 mV to −7.66 ± 0.29 for unexposed and RMF-exposed bacteriophages, respectively.     

Cryo-EM structure of the heptameric calcium homeostasis modulator 1 channel

Calcium homeostasis modulator 1 (CALHM1) is a voltage- and Ca²⁺-gated ATP channel that plays an important role in neuronal signaling. However, as the previously reported CALHM structures are all in the ATP-conducting state, the gating mechanism of ATP permeation is still elusive. Here, we report cryo-EM reconstructions of two Danio rerio CALHM1 heptamers with ordered or flexible long C-terminal helices at resolutions of 3.2 Å and 2.9 Å, respectively, and one D. rerio CALHM1 octamer with flexible long C-terminal helices at a resolution of 3.5 Å. Structural analysis shows that the heptameric CALHM1s are in an ATP-nonconducting state with a central pore diameter of approximately 6.6 Å. Compared with those inside the octameric CALHM1, the N-helix inside the heptameric CALHM1 is in the “down” position to avoid steric clashing with the adjacent TM1 helix. Molecular dynamics simulations show that as the N-helix moves from the “down” position to the “up” position, the pore size of ATP molecule permeation increases significantly. Our results provide important information for elucidating the mechanism of ATP molecule permeation in the CALHM1 channel.     

APLP2 Regulates Refractive Error and Myopia Development in Mice and Humans

Myopia is the most common vision disorder and the leading cause of visual impairment worldwide. However, gene variants identified to date explain less than 10% of the variance in refractive error, leaving the majority of heritability unexplained (“missing heritability”). Previously, we reported that expression of APLP2 was strongly associated with myopia in a primate model. Here, we found that low-frequency variants near the 5’-end of APLP2 were associated with refractive error in a prospective UK birth cohort (n = 3,819 children; top SNP rs188663068, p = 5.0 × 10⁻⁴) and a CREAM consortium panel (n = 45,756 adults; top SNP rs7127037, p = 6.6 × 10⁻³). These variants showed evidence of differential effect on childhood longitudinal refractive error trajectories depending on time spent reading (gene x time spent reading x age interaction, p = 4.0 × 10⁻³). Furthermore, Aplp2 knockout mice developed high degrees of hyperopia (+11.5 ± 2.2 D, p < 1.0 × 10⁻⁴) compared to both heterozygous (-0.8 ± 2.0 D, p < 1.0 × 10⁻⁴) and wild-type (+0.3 ± 2.2 D, p < 1.0 × 10⁻⁴) littermates and exhibited a dose-dependent reduction in susceptibility to environmentally induced myopia (F(2, 33) = 191.0, p < 1.0 × 10⁻⁴). This phenotype was associated with reduced contrast sensitivity (F(12, 120) = 3.6, p = 1.5 × 10⁻⁴) and changes in the electrophysiological properties of retinal amacrine cells, which expressed Aplp2. This work identifies APLP2 as one of the “missing” myopia genes, demonstrating the importance of a low-frequency gene variant in the development of human myopia. It also demonstrates an important role for APLP2 in refractive development in mice and humans, suggesting a high level of evolutionary conservation of the signaling pathways underlying refractive eye development.     

Forces of a single-beam gradient laser trap on a dielectric sphere in the ray optics regime

We calculate the forces of single-beam gradient radiation pressure laser traps, also called “optical tweezers,” on micron-sized dielectric spheres in the ray optics regime. This serves as a simple model system for describing laser trapping and manipulation of living cells and organelles within cells. The gradient and scattering forces are defined for beams of complex shape in the ray-optics limit. Forces are calculated over the entire cross-section of the sphere using TEM₀₀ and TEM₀₁^* mode input intensity profiles and spheres of varying index of refraction. Strong uniform traps are possible with force variations less than a factor of 2 over the sphere cross-section. For a laser power of 10 mW and a relative index of refraction of 1.2 we compute trapping forces as high as ~ 1.2 × 10^-6 dynes in the weakest (backward) direction of the gradient trap. It is shown that good trapping requires high convergence beams from a high numerical aperture objective. A comparison is given of traps made using bright field or differential interference contrast optics and phase contrast optics.     

Inactivation of rubella virus by gamma radiation

The Gilchrist and M-33 strains of rubella virus exposed in the frozen state to ¹³⁷Ce or ⁶⁰Co were inactivated exponentially according to “one hit” kinetics. There was no difference in the radiosensitivity of the two strains. Experimental D₃₇ values for both strains ranged from 1.9 × 10⁵ to 2.9 × 10⁵ rads, and computed radiosensitive molecular weights ranged from 2.6 × 10⁶ to 4.0 × 10⁶ daltons.     

Molecular Fingerprint and Dominant Environmental Factors of Nitrite-Dependent Anaerobic Methane-Oxidizing Bacteria in Sediments from the Yellow River Estuary,China

Nitrite-dependent anaerobic methane oxidation (n-damo) is performed by “Candidatus Methylomirabilis oxyfera” (M. oxyfera), which connects the carbon and nitrogen global nutrient cycles. In the present study, M. oxyfera-like bacteria sequences were successfully recovered from Yellow River Estuary sediments using specific primers for 16S rRNA and pmoA genes. A M. oxyfera-like sequences analysis based on the 16S rRNA gene revealed greater diversity compared with the pmoA gene; the 16S rRNA gene sequences retrieved from the Yellow River Estuary sediments belong to groups A as well as B and were mainly found in freshwater habitats. Quantitative PCR showed that 16S rRNA gene abundance varied from 9.28±0.11×10³ to 2.10±0.13×10⁵ copies g^-1 (dry weight), and the pmoA gene abundance ranged from 8.63±0.50×10³ to 1.83±0.18×10⁵ copies g^-1 (dry weight). A correlation analysis showed that the total organic carbon (TOC) and ammonium (NH₄ ⁺) as well as the ratio of total phosphorus to total nitrogen (TP/TN) influenced the M. oxyfera-like bacteria distribution in the Yellow River Estuary sediments. These findings will aid in understanding the n-damo bacterial distribution pattern as well as their correlation with surrounding environmental factors in temperate estuarine ecosystems.     

Genomic Assortative Mating in Marriages in the United States

Assortative mating in phenotype in human marriages has been widely observed. Using genome-wide genotype data from the Framingham Heart study (FHS; number of married couples = 989) and Health Retirement Survey (HRS; number of married couples = 3,474), this study investigates genomic assortative mating in human marriages. Two types of genomic marital correlations are calculated. The first is a correlation specific to a single married couple “averaged” over all available autosomal single-nucleotide polymorphism (SNPs). In FHS, the average married-couple correlation is 0.0018 with p = 3×10⁻⁵; in HRS, it is 0.0017 with p = 7.13×10⁻¹³. The marital correlation among the positively assorting SNPs is 0.001 (p = .0043) in FHS and 0.015 (p = 1.66×10⁻²⁴) in HRS. The sizes of these estimates in FHS and HRS are consistent with what are suggested by the distribution of the allelic combination. The study also estimated SNP-specific correlation “averaged” over all married couples. Suggestive evidence is reported. Future studies need to consider a more general form of genomic assortment, in which different allelic forms in homologous genes and non-homologous genes result in the same phenotype.