Antihyperalgesic effect of simultaneously released hydromorphone and bupivacaine from polymer fibers in the rat chronic constriction injury model

We aimed to evaluate the antihyperalgesic efficacy of a combination of hydromorphone (HM) and bupivacaine (BP) delivered via controlled release from a biodegradable cylindrical rod. In vivo studies were performed using a rat model of thermal hyperalgesia induced by chronic constriction injury (CCI) of the sciatic nerve with loose ligatures. Poly(lactic-co-glycolic acid) (PLGA) rods (10 mm length, 1 mm diameter) loaded with HM (5 mg per rod), BP (5 mg per rod) or no drug (placebo) were implanted subcutaneously, in single or dual pairs, adjacent to the constriction injury, immediately after nerve ligation. We evaluated the efficacy of two dose levels for each drug, alone or in combination, in attenuating thermal hyperesthesia over a period of 12 days according to a prevention protocol. Plasma levels of drugs released from the rods and also released in an in vitro simulation were evaluated. In vitro studies demonstrated that drug release is maintained for at least 10 days. HM (5 mg) alone and BP (5 mg) alone did not attenuate hyperalgesia. Their combination provided a significant increase in the paw withdrawal latency as compared to single agents or placebo. When the dose in each group was doubled, implanting four rods, significant attenuation of hyperalgesia was observed. Analyses of rods retrieved after termination of experiments (after 12 days) revealed 30% residual HM and 70% residual BP content. Prolonged delivery of HM and BP alone or in combination via locally applied PLGA rods may offer a feasible alternative to provide long-lasting analgesia.     

Cyanobacterial phycobilisomes. Particles from Synechocystis 6701 and two pigment mutants

The phycobilisomes of the unicellular cyanobacterium Synechocystis 6701, grown in white light, contain C-phycoerythrin, C-phycocyanin, and allophycocyanin in a molar ration of approximately 2:2:1, and in addition, polypeptides of 99, 46, 33.5, 31.5, 30.5, and 27 x 10(3) Daltons, as well as a trace of a approximately 9 x 10(3)-dalton component. Two nitrosoguanidine-induced mutants of this organism produce aberrant phycobilisomes. Crude cell extracts of these mutants, 6701-NTG25 and NTG31, contain phycoerythrin, phycocyanin, and allophycocyanin in a molar ration of 1:5:1:1 and 0.55:0.3:1.0, respectively. The phycobilisomes from both mutants lack the 33.5 x 10(3)-dalton polypeptide. Wile-type phycobilisomes consist of a core composed of an equilateral array of three cylindrical elements surrounded by six rods in a fanlike arrangement. The rods are made up of stacked disks, 11 nm in diameter and 6 nm thick. In phycobilisomes of mutant 6701-NTG25, numerous particles with fewer than six rods are seen. Mutant 6701-NTG31 produces incomplete structures that extend from triangular core particles, through cores with one or two attached rods, to cores with as many as five rods. The structure of the core appears unaltered throughout. The amount of phycocyanin (relative to allophycocyanin) appears to determine the number of rods per core. A common assembly form seen in 6701-NTG31 is the core with two rods attached at opposite sides. From observations of this form, it is concluded that the core elements are cylindrical, with a height of 14 nm and a diameter of 11 nm. No consistently recognizable structural details are evident within the core elements.     

Radiographic inspection of porosity in pure titanium dumbbell castings

Radiographic inspection of porosity in pure titanium dumbbell castings Background: Titanium frameworks are frequently indicated for implant supported prostheses; however, voids are usually encountered inside cast titanium. Objective: This study aimed to confirm the efficacy of a radiographic technique for inspection of porosity in commercially pure titanium castings with different diameter. Materials and methods: Sixty dumbbell rods (n = 20) with a central 1.5, 2.0 and 3.5 mm diameter were prepared by lost‐wax casting. Cast specimens were finished and polished and submitted to radiographic examination (90 kV, 15 mA, 0.6 s and 10–13 mm of distance) using periapical film. The radiographs were visually analysed for the presence of porosity in the extension of the dumbbell or in the central portion of the rods. Data were submitted to Pearson Chi‐square test (5%). Results: The tested radiographic method proved to be suitable for the evaluation of cast frameworks. Internal porosities were observed in most of the specimens (91.7%) (p = 0.0005); however, only 20% occurred on the central portion of the rods (p = 0.612). Conclusion: Internal porosities can be visualised through radiographs and occur mostly in small diameter structures. The radiographic evaluation of metal structures can improve the quality of frameworks and thereby potentially increase the longevity of the rehabilitation.     

3个温带阔叶树种根系长期分解速率研究

根系分解对土壤碳固持和养分长期有效性具有重要意义,但目前对根系的长期分解模式仍知之甚少。比较3个温带阔叶树种不同直径根系7 a分解动态,可为生态过程模型提供数据支撑。在帽儿山生态站采用分解袋法对白桦（Betula platyphylla）、春榆（Ulmus davidiana var.japonica）、水曲柳（Fraxinus mandshurica）的5个直径等级（< 1 mm）、（1-2 mm）、（2-5 mm）、（5-10 mm）、（10-20 mm）根系进行了7 a野外分解实验。重复测量方差分析表明：时间、树种、直径与树种交互作用、树种与时间交互作用显著影响根系质量保持率。根系质量保持率随时间呈指数下降趋势,7 a间根系经历早期快速分解和后期慢速分解两个阶段,实验结束时根系仍剩余相当部分的初始质量（24%-56%）。利用Olson指数衰减模型估计各树种根系分解系数发现：白桦根系分解系数与根直径间具有显著的线性正相关关系,水曲柳具有显著对数正相关关系,春榆的关系不显著。3个树种短期分解系数均高估根系分解速率,而且不能完全代表长期分解系数的种内、种间差异。研究结果对理解根系长期分解速率随直径变化模式提供了数据支撑。     

Rod sensitivity during Xenopus development

We have measured the sensitivity of rod photoreceptors from overnight-dark-adapted Xenopus laevis through developmental stages 46-66 into adulthood by using suction-pipette recording. The dark current increased gradually from approximately 5 pA at stage 46 to approximately 20 pA at stage 57, compared with an adult (metamorphosed) current of approximately 35 pA. This increase in dark current largely paralleled the progressive increase in length and diameter of the rod outer segment (ROS). Throughout stages 46-66, the dark current increased approximately linearly with ROS surface area. At stage 53, there was a steep (approximately 10-fold) increase in the rod flash sensitivity, accompanied by a steep increase in the time-to-peak of the half-saturated flash response. This covariance of sensitivity and time-to-peak suggested a change in the state of adaptation of rods at stage 53 and thereafter. When the isolated retina was preincubated with 11-cis-retinal, the flash sensitivity and the response time-to-peak of rods before stage 53 became similar to those at or after stage 53, suggesting that the presence of free opsin (i.e., visual pigment without chromophore) in rods before stage 53 was responsible for the adapted state (low sensitivity and short time-to-peak). By comparing the response sensitivity before stage 53 to the sensitivity at/after stage 53 measured from rods that had been subjected to various known bleaches, we estimated that 22-28% of rod opsin in stage 50-52 tadpoles (i.e., before stage 53) was devoid of chromophore despite overnight dark-adaptation. When continuously dark adapted for 7 d or longer, however, even tadpoles before stage 53 yielded rods with similar flash sensitivity and response time-to-peak as those of later-stage animals. In conclusion, it appears that chromophore regeneration is very slow in tadpoles before stage 53, but this regeneration becomes much more efficient at stage 53. A similar delay in the maturity of chromophore regeneration may partially underlie the low sensitivity of rods observed in newborn mammals, including human infants.     

Formation of the cylindrical structure during the acrosome reaction of abalone spermatozoa

Spermatozoa of abalone Haliotis discus were examined before and during the acrosome reaction with special regard to one of the newly formed structures: a cylindrical structure surrounding a part of the elongated acrosomal process near the opening of the acrosomal vesicle. The structure, about 0.2 μm in diameter and about 1 μm in length, was revealed to be composed of a tightly coiled, fine tubular structure about 20 nm in diameter. In the course of the acrosome reaction, a triple-spiral structure appeared in the anterior part of the acrosomal vesicle. Since this spiral structure was also composed of a tightly coiled 20 nm tubule(s), it was concluded that this structure was transformed into the single-walled cylindrical structure by simple stretching in the direction of its longitudinal axis. In the clumps of spermatozoa that underwent acrosome reaction in suspension, the cylindrical structures were frequently found in contact with each other and/or other structures, indicating that they are very sticky.     

水曲柳和落叶松不同根序之间细根直径的变异研究

细根直径大小和根序高低对细根寿命和周转估计具有重要的影响,研究不同根序之间的直径变异对认识细根直径与根序的关系具有重要意义。该文根据Pregitzer等(2002)提供的方法,研究了位于东北林业大学帽儿山实验林场尖砬沟森林培育实验站17年生水曲柳(Fraxinus mandshurica)和落叶松(Larix gmelinii)人工林细根1~5级根序的平均直径的变化、直径的最小值和最大值范围、直径的变异系数。结果表明,水曲柳和落叶松细根直径<2 mm时,包含5个根序,随着根序由小到大的增加,细根直径也在增大。各根序平均直径之间,存在较大的差异。在同一根序内,细根直径范围很大,水曲柳和落叶松一级根最小直径均<0.20 mm,最大直径分别<0.50 mm(水曲柳)和<0.70 mm(落叶松)左右。2~3级根序直径最小值在0.20~0.30 mm之间,最大值≤1.0 mm。5级根直径最小值<1.0 mm,最大值超过2.0 mm。随着根序等级增加,直径变异系数增大。一级根序的直径平均变异系数<10%,2~3级根序直径平均变异系数在10%~15%左右,4~5级根序直径的平均变异系数在20%~30%之间。因此,在细根寿命与周转研究过程中,必须同时考虑直径和根序对细根的寿命估计的影响。     

Vertical migration of adult Ixodes rubicundus,the Karoo paralysis tick (Acari: Ixodidae)

Mortality due to Karoo paralysis amongst livestock is of considerable economic importance in South Africa. Indications are that the extent of vertical migration of adult ticks, to reach questing positions on grasses, is influenced by sudden climatic chages. Such influences as well as selection of questing substrates were investigated under controlled conditions. Vertical migration of adult Ixodes rubicundus on copper rods was determined in a square metal arena within a closed glass container in a room in which temperature and light could be controlled. Significantly more female and male ticks migrated vertically on 1.5 mm diameter rods than on 4.0 mm rods and on 450 mm long rods than on 100 mm rods. More ticks of both sexes migrated vertically at RH>80% than at RH<50% and at 12°C than at 21°C. More female than male and more older than younger ticks migrated vertically in all experiments. The results of this study contribute towards an understanding of the epidemiology of Karoo paralysis.     

Theoretical Considerations on the Responses of Gold-Deposited Surface Plasmon Resonance-Based Glass Rod Sensors Using a Three-Layer Fresnel Equation

The response curves of gold (Au)-deposited surface plasmon resonance-based glass rod sensors were calculated using a three-layer Fresnel equation while considering various parameters for the sensor system calculations. Au films with thicknesses of 30, 45, and 70 nm were deposited on half of the surfaces of the glass rods, which were 2 mm in diameter, with a deposition length of 100 mm. Sensor elements with Au film thicknesses of 45 nm on glass rods with diameters of 1 and 4 mm and with deposition lengths of 10, 20, and 50 mm were also prepared. The sensor system consists of a light-emitting diode (LED) with a wavelength of 654 nm as the light source with a mini-spectrometer as the detector. The LED intensity distribution, the range of the angle of incidence of light into the sensor element, and the thickness distributions of the Au films deposited on the glass rods were considered to be the important parameters for the calculations. The minimum positions of all the theoretical response curves agreed well with those of the experimental response curves within the limits of the experimental and theoretical uncertainties. Most of the overall response characteristics of the theoretical curves agreed well with those of the experimental curves within the limits of both types of uncertainty. It was found that the thickness distribution of the deposited Au film in the cross-sectional direction dominates the sensor response and thus is the most important parameter for calculation of the sensor properties. The agreements between the experimental and theoretical response curves indicate both the potential and the usefulness of the sensor performance estimation process based on the three-layer Fresnel equation.     

Photoreceptor fine structure in the southern fiddler ray (Trygonorhina fasciata).

The fine structure of the retinal photoreceptors has been studied by light and electron microscopy in the southern fiddler ray or guitarfish (Trygonorhina fasciata). The duplex retina of this species contains only rods and single cones in a ratio of about 40:1. No multiple receptors (double cones), no repeating pattern or mosaic of photoreceptors and no retinomotor movements of these photoreceptors were noted. The rods are cylindrical cells with inner and outer segments of the same diameter. Cones are shorter, stouter cells with a conical outer segment and a wider inner segment. Rod outer segment discs display several irregular incisures to give a scalloped outline to the discs while cone outer segment discs have only a single incisure. In all photoreceptors a non-motile cilium joins the inner and outer segments. The inner segment is the synthetic centre of photoreceptors and in this compartment is located an accumulation of mitochondria (the ellipsoid), profiles of both rough and smooth endoplasmic reticulum, prominent Golgi zones and frequent autophagic vacuoles. The nuclei of rods and cones have much the same chromatin pattern but cone nuclei are invariably located against or particularly through the external limiting membrane (ELM). Numerous Landolt's clubs which are ciliated dendrites of bipolar cells as well as Müller cell processes project through the ELM, which is composed of a series of zonulae adherentes between these cells and the photoreceptors. The synaptic region of both rods (spherules) and cones (pedicles) display both invaginated (ribbon) synapses and superficial (conventional) synapses with cones showing more sites than the rods.     

Interpretation of Diffusion Susceptibility Data Obtained with 50-μg Carbenicillin Discs Against Gram-Negative Organisms

A total of 284 clinical isolates of various species of Enterobacteriaceae, Pseudomonas aeruginosa, P. maltophilia, and Acinetobacter anitratum were tested for susceptibility to carbenicillin by the standardized Bauer-Kirby disc diffusion technique and a microtiter broth dilution method. The data obtained led to the following proposed criteria for the interpretation of the results of disc susceptibility tests. Enterobacteriaceae that yield zones of inhibition equal to or greater than 20 mm in diameter around 50-mug discs of carbenicillin are designated as sensitive to the drug; isolates that yield zones measuring from 18 to 19 mm in diameter are reported as of equivocal (intermediate) susceptibility to the drug, whereas those enterobacterial isolates that are characterized by zones of inhibition of 17 mm or less in diameter are interpreted as resistant to carbenicillin. Isolates of P. aeruginosa, P. maltophilia, and A. anitratum yielding zones of 14 mm or more in diameter around 50-mug discs of carbenicillin are reported as sensitive, whereas those isolates that are characterized by zones of 13 mm or less in diameter are reported as resistant to this drug.     

Biomechanical assessment of a PEEK rod system for semi-rigid fixation of lumbar fusion constructs

The concept of semi-rigid fixation (SRF) has driven the development of spinal implants that utilize nonmetallic materials and novel rod geometries in an effort to promote fusion via a balance of stability, intra- and inter-level load sharing, and durability. The purpose of this study was to characterize the mechanical and biomechanical properties of a pedicle screw-based polyetheretherketone (PEEK) SRF system for the lumbar spine to compare its kinematic, structural, and durability performance profile against that of traditional lumbar fusion systems. Performance of the SRF system was characterized using a validated spectrum of experimental, computational, and in vitro testing. Finite element models were first used to optimize the size and shape of the polymeric rods and bound their performance parameters. Subsequently, benchtop tests determined the static and dynamic performance threshold of PEEK rods in relevant loading modes (flexion-extension (F/E), axial rotation (AR), and lateral bending (LB)). Numerical analyses evaluated the amount of anteroposterior column load sharing provided by both metallic and PEEK rods. Finally, a cadaveric spine simulator was used to determine the level of stability that PEEK rods provide. Under physiological loading conditions, a 6.35 mm nominal diameter oval PEEK rod construct unloads the bone-screw interface and increases anterior column load (approx. 75% anterior, 25% posterior) when compared to titanium (Ti) rod constructs. The PEEK construct's stiffness demonstrated a value lower than that of all the metallic rod systems, regardless of diameter or metallic composition (78%??80% reduction in F/E, p??70% reduction in LB, p??54% reduction in AR, p?相似文献   

Significance of determining novobiocin sensitivity in the taxonomy of staphylococci

Novobiocin sensitivity of 96 strains belonging to various staphylococcal species was studied. It was noted that Staph. saprophyticus significantly differed from Staph. aureus and Staph. epidermidis with respect to the above antibiotic. The MIC up to 2 micrograms/ml and the growth inhibition zones of 26--35 mm in diameter were characteristic of Staph. aureau and Staph. epidermidis, while the respective figures for most of the strains of Staph. saprophyticus were 32--64 micrograms/ml and 12--17 mm. However, 28 percent of the strains of Staph. saprophyticus did not differ with respect to their movobiocin sensitivity from the other 2 species. It is concluded that the "novobiocin test" may be used for differentiation of staphylococci, within the genera. At the same time it was shown that the method of the paper sensitivity discs compares very favourably with the method of serial dilutions in agar not only because of its simplicity and convenience of manipulation with single strains, but also of the possibility of identifying the population heterogenicity with respect to novobiocin sensitivity.     

Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation

Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage.Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions.The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the “tooth-restoration” interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material.     

Structure of wall layers in Selaginella kraussiana microspores (Lycophyta)

A similarity was found in both construction and ultrastructure between the two exospore layers in microspores of Selaginella kraussiana. The exospore is made up of two different kinds of rods. One of the kinds of rods are large, 100–150 nm in width, while the other are tubular rods 10–15 nm in diameter. The large rods are wider at the base of the spines than in the upper part, possibly due to flattening or compression. Both the outer and the inner exospores have a stranded surface that is very pronounced in the microspores of this species. Fibrous strands persisting the scanning electron microscope and transmission electron microscope (TEM) fixations were observed on the spore surface proximally and through perforations (exospore channel openings). This net of fibres penetrates and fills the space of the cavities within large channels through the outer and inner exospore and within the gap. According to our interpretation, these strands would be produced by the tapetum and are probably related to the nourishment of the developing microspores. Contrast varies in TEM sections after cytochemical stains, but this appears to be due to transitory substances, e.g. carbohydrates, rather than to be a substantial difference in basic composition between inner and outer exospore layers.     

Filamentous Bacterial viruses

The filamentous bacterial virus is a simple and well-characterized model system for studying how genetic information is transformed into molecular machines. The viral DNA is a single-stranded circle coding for about 10 proteins. The major viral coat protein is largely α-helical, with about 46 amino acid residues. Several thousand identical copies of this protein in a helical array form a hollow cylindrical tube 1–2μ long, of outer diameter 60 Å and inner diameter 20 Å, with the twisted circular DNA extending down the core of the tube. Before assembly, the viral coat protein spans the cell membrane, and assembly involves extrusion of the coat from the membrane. X-ray fibre diffraction patterns of the Pf 1 species of virus at 4°C, oriented in a strong magnetic field, give three-dimensional data to 4 Å resolution. An electron density map calculated from native virus and a single iodine derivative, using the maximum entropy technique, shows a helix pitch of 5.9 Å. This may indicate a stretched A-helix, or it may indicate a partially 3₁₀ helix conformation, resulting from the fact that the coat protein is an integral membrane protein before assembly, and is still in the hydrophobic environment of other coat proteins after assembly.     

A simple model describing the elastic properties of human umbilical arterial smooth muscle

Elastic properties of cylindrical segments of 71 normal double and 4 single human umbilical arteries were studied. This specimen is rich in vascular smooth muscle in comparison with other great arteries. Outer diameter versus intraluminal pressure characteristic curves were taken with decreasing pressures in vitro in different contraction states. Tangential force and circumferential incremental elastic modulus were computed. A sum of 222 curves was analysed. The investigations showed that if we take tangential force and outer radius values measured at the same pressure levels but in different contraction states, then a similar proportional change in tangential force will induce a similar proportional passive change in the outer radius, to some extent independently of the degree of active tangential shortening of the segment. For example to induce a 10% passive decrease of the outer radius from values measured at 100 mm Hg intraluminal pressure, tangential force had to be decreased by 76.7 +/- 9.9% in single relaxed arteries, and by 79.6 +/- 0.8% in normal double relaxed segments. These values corresponded to intraluminal pressure levels of 26.4 +/- 4.9 mm Hg and 23.1 +/- 0.9 mm Hg, respectively. In 30% active spontaneous shortening to reach the same 10% passive decrease in outer radius from the value measured at 100 mm Hg, tangential force had to be decreased by 75.2 +/- 1.9% which corresponded to 29.6 +/- 20 mm Hg. The same values in 5-HT induced contraction, 30% active shortening were 76.7 +/- 2.0% and 28.4 +/- 2.6 mm Hg, respectively. In addition to the similarity of relative changes in tangential force, the pressure levels were to some extent also similar. These data suggest that elastic elements in the human umbilical arterial smooth muscle may be organized in such a way as to ensure similar prestretch of similar elastic elements at similar pressures independently of the degree of active shortening of the circumference.     

Moderate alcohol consumption is associated with better endothelial function: a cross sectional study

Background

Natural heterologous valved conduits with a diameter greater than 22 mm that can be used for right ventricular outflow tract reconstruction in adults are not commercially available. The purpose of this study was to measure by ultrasonography the maximum diameter of the distended jugular veins of horses and cattle, respectively, to identify a population of animals that would be suitable for post-mortem collection of jugular veins at sizes greater than 22 mm.

Methods

The study population included 60 Warmblood horses, 25 Freiberger horses, 20 Brown Swiss cows, and 20 Holstein cows (including 10 Holstein and 10 Red Holstein). The maximum cross-sectional diameter of the distended jugular veins was measured at a location half-way between the mandibular angle and the thoracic inlet. The thoracic circumference (heart girth length) was used as a surrogate of body size. The jugular vein diameters of the different populations were compared by analysis of variance and the association between heart girth length and jugular vein diameter was determined in each of the four study populations by linear regression analysis.

Results

There was considerable individual variation of jugular vein diameters within each of the four study populations. There was no statistically significant relationship between thoracic circumference and jugular vein diameter in any of the populations. The jugular vein diameters of Brown Swiss cows were significantly larger than those of any of the other populations. Warmblood horses had significantly larger jugular vein diameters compared to Freiberger horses.

Conclusion

The results of this study suggest that the production of bovine or equine xenografts with diameters of greater than 22 mm would be feasible. Differences between species and breeds need to be considered. However, prediction of the jugular vein diameter based on breed and heart girth length in an individual animal is inaccurate.