99mTc labelled model drug carriers - labeling, stability and organ distribution in rats

The surface characteristics of intravenously administered particulate drug carriers decisively influence the protein adsorption that is regarded as a key factor for the in vivo fate of the carriers. We labeled surface-modified polymer particles with the gamma-emitting radioisotope 99mTc in order to test their properties in blood and follow their in vivo fate. The biodistribution was different in various types of polymer particles. As expected, labeled particles were found in the mononuclear phagocyte system in a large scale but markedly different biodistribution for some particles were also shown.     

利用低真空环境在地面模拟载人航天器内部气体对流散热的探讨

为研究相应的模拟实验方法并建立载人航天器内部环境的地面模拟装置，克服地面上模拟微重力气体对流散热的困难，本文提出了地面以低真空技术减弱自然对流模拟载人航天器内啊对流热的实验方法，建立合适的试验舱和采用合适的实验方法，以便通过实验对环境控制与生命保障系统的设备作出评价。     

Polyvinyl alcohol sponge for embolotherapy: particle size and morphology

The size and morphology of particulate polyvinyl alcohol (PVA) sponge prepared by a blender technique for embolotherapy were analyzed by light and scanning electron microscopy. Techniques for preparation and sizing of PVA sponge particles are described. Two types of particulate material, differing in both size and morphology, were found. Large particles (greater than 50 micron) had irregular shapes and sharp, jagged edges. Smaller particles (2-50 micron) were more numerous. Attempts to characterize the smaller particles were unsuccessful. Preparation of PVA sponge particles using the blender technique is a viable choice in external carotid neuroembolization procedures. However, the potential effects of small particles possibly causing cranial nerve palsies does need consideration.     

空间飞行器防结露舱壁的轻量化分析

目的：研究采用隔热及通风的防结露措施后空间飞行器密封舱壁的质量构成特点,为舱壁的轻量化设计提供依据。方法：建立了舱壁传热过程的物理数学模型和质量构成模型,对结露临界工况下影响质量增量的几个因素进行了分析。结果：在其它条件下变时,随着通风量的增加,系统的质量增量会先减小然后增大,存在最小值及相应的临界通风量。找出了通风量、隔热层表面黑度及隔热层导热系数对质量增量的影响规律以及露点变化的影响。结论：较小的隔热层导热系数,较低的外表面黑度和较高的内表面黑度,均有利于舱壁质量增量的降低。     

Trisacryl gelatin microspheres for therapeutic embolization,I: development and in vitro evaluation.

PURPOSETo develop a precisely calibrated, perfectly spherical, stainable, soft, and implantable but nonresorbable particulate embolization material.METHODSCalibrated particles with a trisacryl gelatin polymer core and hydrophilic surface characteristics were obtained by reversed emulsion synthesis followed by application of a wet-sieving technique. Particles were suspended in saline, bottled, and sterilized. Quality control included analysis of particle diameters before and after sieving and of suspension sterility and apyrogenicity. Particles were subsequently tested to ascertain their compatibility with commercially available microcatheters.RESULTSThe resulting embolization material consisted of spherical, stainable microspheres of medical grade with diameters ranging from 130 microns to 1200 microns. Sieving the suspension produced particle groups of homogeneous size (accuracy, +/- 20-100 microns). At injection, the particles showed no tendency to build aggregates or to obstruct the microcatheters.CONCLUSIONPrecisely calibrated and easy-to-use microspheres were obtained that satisfied the biomedical requirements for implantation as an embolization material.     

密闭环境中悬浮颗粒物上附着微生物的检测

目的 分析检测密闭环境中县浮颗粒物上附着微生物的种类及数量。为航天器舱内大气污染的控制和监测提供参数依据。方法 依据Ｕ．Ｓ．Ａ ＥＰＡ ＩＰ－１０方法,在密闭环境中用大流量冲击式采样器分３级连续采样,颗粒物的空气动力学直径（ＡＤ）分别为：１００μｍ≥ＡＤ〉１０μｍ、１０μｍ≥ＡＤ〉２μｍ及ＡＤ≤２μｍ。选择室外较洁净空气以同样方法采样作为对照。对采集的颗粒物精密称量。分别培养颗粒物上的吸附微生物,     

Heat stress evaluation of anti-exposure flight garments

Constant-wear anti-exposure suit ensembles, employing a polytetrafluoroethylene (PTFE) coverall, were evaluated for their impact on aircrew performance under heat stress. Conditions were designed to simulate stresses experienced by aircrews during aircraft operations over cold water; therefore, chamber temperatures were maintained at dry bulb temperature = 34.0 +/- 1.5 degrees C and wet bulb temperature = 23.9 +/- 4.5 degrees C. Six subjects were studied twice in each of five configurations, i.e., a standard flight ensemble (control), and four combinations of the PTFE coverall with different liners, for maximum 180-min exposures. Subjects alternated periods of physical work, performance of a psychomotor task, and rest, for a total time of 20 min in each activity cycle, which were repeated throughout the duration of a trial, at an estimated mean metabolic rate of 2.4 kcal.min-1. Mean test duration for the control was 177 +/- 9 min, while for the other configurations, mean test durations were 105 +/- 32 min, with no significant differences observed between the PTFE-based configurations. Total sweat rate (SRT), heat storage rate (S), final heart rate (HR), and mean weighted skin temperature (Tsk) indicated similar trends among configurations, with significant differences principally observed as a consequence of the use of the PTFE coverall. Use of the PTFE coverall appears to limit heat tolerance to less than 3 h if a moderate workload is imposed under heat stress.     

Early experience with the GORE-TEX polytetrafluoroethylene anterior cruciate ligament prosthesis

A prospective study of 41 patients with acute and chronic ACL deficiency underwent reconstruction with the GORE-TEX polytetrafluoroethylene (PTFE) ACL prosthesis beginning in November 1983. Thirty-nine patients who were at least 2 years from their surgical procedure were available for follow-up evaluation, which included subjective questionnaire, clinical examination, and instrumented ligamentous laxity tests. Eight patients had an acute injury to the ACL and 31 patients had chronic ACL insufficiency for which reconstruction was performed. Thirty-four patients had satisfactory results, allowing full return to activity with no appreciable symptomatology. Of the remaining five patients, four had a complete rupture of the prosthesis. The average knee arthrometric measurement improved from a 5.4 mm left/right difference preoperatively to a 2.0 mm left/right difference at 2 year followup. Nine patients had postoperative complications of one or more atraumatic episodes of a sterile effusion. Six patients had recurrent effusions; in five, arthroscopy revealed partial tears of less than one-third of the prosthesis. Three patients who had recurrent effusions had PTFE particles in their synovial biopsies. One patient had an immediate postoperative infection and to data has had salvage of the prosthesis and currently has a stable knee with full return to activities. Based on the early results of this study, the GORE-TEX PTFE ACL prosthesis provided a satisfactory method of reconstruction for ACL deficient knees. Based on the evaluation used, 87% of the patients had satisfactory results. Problems associated with use of this prosthesis include partial or complete tears of the prosthesis and sterile effusions, possibly due to synovial irritation from the PTFE particles.(ABSTRACT TRUNCATED AT 250 WORDS)     

空间飞行器内结露的理论分析及模拟实验

目的 探讨防止载人空间飞行器舱内结露的方法 。方法 从热力学和传热学的角度分析和研究了空间飞行吕同的结露条件及过程,对影响舱内结露的几个因素进行了探讨。结果 壁面隔热有利于防止结露,局部通风有可能抑制结露。但单独采用隔热或通风的方法均存在一定的局限性,降低外壁黑度有利于防止舱内结露。结论 采用壁面隔热和局部通风相结合的方法。可以有效地达到防止结露的目的。     

Accuracy of aimed arm movements in changed gravity.

We studied the accuracy of aimed arm movements in normal gravity, and during the hypergravity (hyper-G) and microgravity (micro-G) episodes of KC-135 parabolic flights. Subjects pointed at mirror-viewed targets without sight of their arm, and final pointing position was measured by a digitizing pad. Compared with the normal gravity (normal-G) baseline, subjects pointed consistently higher in hyper-G, and still higher in micro-G. Results were not different if subjects viewed targets only during normal-G and pointed at their memorized position under changed gravity (changed-G); this suggests that the "elevator illusion" played a minor role in our study. The observed impairments were attributed to degraded proprioceptive feedback and/or inappropriate motor programs in changed-G. Pointing accuracy improved movement-to-movement but not parabola-to-parabola, indicating that prolonged exposure is needed for sustained adaptation.     

Influence of the stopcock on the efficiency of percutaneous drainage catheters: laboratory evaluation.

The effects of stopcocks on percutaneous fluid drainage were tested in a laboratory model by using a standard stopcock (6-French inner diameter) and a prototype stopcock (9-French inner diameter) connected to 8-, 10-, 12-, 14-, and 16-French catheters. Catheters were immersed in water alone or in viscous fluid with particulate matter, and the system was connected to low wall suction or gravity drainage. The average volume of fluid aspirated in a given period with and without a stopcock was compared for each catheter. The standard stopcock decreased drainage efficiency for these catheters by 13-42%. This decreased drainage efficiency was worse with the larger catheters. Particulate fluid blocked the stopcock connection for all catheters. With the prototype stopcock, drainage of water alone was reduced by 0-9% for the catheters of different sizes. Particulate fluid did not obstruct the prototype stopcock with any size catheter. With gravity drainage, the volume of water aspirated was reduced by 12-42% with the standard stopcock and by 3-6% with the prototype stopcock. These data suggest that stopcock connections greatly influence the efficiency of the percutaneous drainage systems. Stopcocks with larger inner diameters may improve drainage over that achievable with the stopcocks that are currently available.     

High energy electron beams characterization using CaSO4:Dy+PTFE phosphors for clinical therapy applications

In the present work high energy electron beam dosimetry from linear accelerator (LINACs) for clinical applications using dysprosium doped calcium sulfate embedded in polytetrafluorethylene (CaSO4:Dy+PTFE) was studied. The irradiations were carried out using high electron beams (6 to 18 MeV) from a linear accelerator (LINAC) Varian, CLINAC 2300C/D, for clinical practice purpose. The electron irradiations were obtained using the water solid in order to guarantee electronic equilibrium conditions (EEC). Field shaping for electron beams was obtained with electron cones. Glow curve and other thermoluminescent characteristics of CaSO4:Dy+PTFE were conducted under high electrons beams irradiations. The TL response of the pellets showed an intensity peak centered at around 215 °C. TL response of CaSO4:Dy+PTFE as a function of high electron absorbed dose showed a linearity in a wide range. To obtain reproducibility characteristic, a set of pellets were exposed repeatedly for the same electron absorbed dose. The results obtained in this study can suggest the applicability of CaSO4:Dy+PTFE pellets for high electron beam dosimetry, provided fading is correctly accounted for.     

Broad exposure screening of air pollutants in the occupational environment of Swedish soldiers deployed in Afghanistan

The main objective of this study was to perform an initial characterization of Swedish soldiers' exposure to air pollutants in Afghanistan and screen for potential health hazards. Stationary monitoring was performed in two military camps, International Security Assistance Force Headquarters in Kabul and Camp Northern Lights in Mazar-e Sharif, at both outdoor and indoor locations. A broad screening including particulate matter (PM10 and PM2.5), polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, n-alkanes, nitrogen dioxide (NO2), sulfur dioxide, toxic metals, and volatile organic compounds (VOCs) was performed over 2 weeks in the autumn of 2009. The results were compared to current air quality guidelines. Particulate matter was identified as the main potential health hazard since military exposure guidelines for marginal effects were exceeded outdoors. In addition, especially in Kabul, levels of particle-bound PAHs and oxy-PAHs were high, whereas levels of toxic metals were generally low. Among gaseous pollutants, elevated NO2 levels in Kabul supported combustion as a major contributor to the poor air quality. VOC levels were generally low, but levels of some pollutants exceeded current guidelines. Because of elevated concentrations of particles with a high content of toxic organics, further monitoring and characterization of the occupational environment are warranted.     

人工重力的生物医学问题：以往工作回顾与面临的挑战

本文首先对现用以运动为主对抗措施的局限性以及将来可能采用以人工重力为主对抗措施的科学依据进行了阐述。进而对两种类型的人工重力－整个航天系统／居住舱全时旋转产生的连续性人工重力和由舱内短臂离心机产生的间断性人工重力的生理学效应及生理学阈限条件进行了回顾。最后对人工重力生物医学研究所面临的挑战和意义进行了介绍。     

The binding parameters of radiolabelled monoclonal F (ab')2 and Fab' fragments relative to immunoglobulin G in reactions with surface-bound antigens.

The binding parameters of iodine-125-labelled intact monoclonal immunoglobulin G (IgG), F(ab')2 and Fab' fragments were compared. The study was carried out with the two monoclonal antibodies (MoAbs) K13 and K16 specific for human Ig light chains kappa and lambda, respectively. When testing the 125I-MoAbs against monodisperse polymer particles coated with the specific antigens, the Ka for the F(ab')2 fragments were similar to that for IgG, while the Ka for the Fab' fragments were reduced to 10%-20% of that for IgG. The number N of effective target sites revealed with Fab' was higher than with F(ab')2 and IgG, presumably because less surface area is occupied by the small Fab' molecules. The immunoreactive fraction F ranged according to IgG greater than F(ab')2 greater than Fab'. The explanation of the moderate difference between the Ka of the monoclonal Fab' and the divalent IgG and F(ab')2 was that the divalent molecules were not divalently attached to the particles. When testing the same antibody preparations against human lymphoma cells producing Ig with light chains kappa or lambda, the binding results were less reliable than when particles were utilised, presumably due to antigen shedding. Different MoAbs vary in their loss of immunoreactivity due to enzymatic degradation and the radiolabelling procedure. The preparation of the radiolabelled fragments should therefore be optimized for each MoAb, and evaluation is necessary before injection. Artificial targets with a low leakage of antigen, like the monodisperse polymer particles here applied, are recommended for the in vitro evaluation of the immunoreactivity of labelled MoAb preparations.     

Collagen-coated acrylic microspheres for embolotherapy: in vivo and in vitro characteristics.

PURPOSETo evaluate the in vivo and in vitro properties of collagen-coated acrylic microspheres and to compare them with polyvinyl alcohol (PVA) particles.METHODSSamples of 100- to 300-microns, 300- to 500-microns, 500- to 700-microns, and 700- to 900-microns collagen-coated acrylic microspheres and 200- to 300-microns PVA particles were suspended in solutions of 50% saline and 50% contrast material. The samples were evaluated for quantitative and qualitative microscopic characteristics (shape, size, deformability); injectability via standardized microcatheters; degree of particulate penetration in the pig rete mirabile; and reaction of tissue to the particles in 48-hour- and 4-week-old specimens.RESULTSThe acrylic microspheres were spherical and deformable. The sample of 100- to 300-microns microspheres (n = 202) had a mean diameter of 210 microns (standard deviation, 43 microns). Hub accumulation, particle aggregation, and catheter occlusion were not observed with the microspheres (all sizes) but were noted with the PVA particles. The 200- to 300-microns PVA particles formed aggregates in the proximal rete. The 100- to 300-microns microspheres were found throughout the rete and beyond. Chronic transmural and perivascular inflammation was observed with the microspheres and the PVA particles.CONCLUSIONSParticle aggregation and catheter occlusion do not complicate the transcatheter delivery of collagen-coated acrylic microspheres as they do with PVA particles. For a given particle and vessel size, acrylic microspheres penetrate to a much greater extent than the PVA particles. Tissue reaction to acrylic microspheres and PVA particles is similar.     

User trial and insulation tests to determine whether shock-absorbing insoles are suitable for use by military recruits during training

A user trial was undertaken to determine whether a shock-absorbing insole is suitable for military use. Two thicknesses of insole (3 mm and 6 mm) were studied and were issued to 38 Royal Marine recruits to wear in their military boots for weeks 12 to 30 of training. Biomechanical measurements showed that both thicknesses of insole significantly (p < 0.05) attenuated the peak pressures generated at heel strike and during forefoot loading when new (relative to a no-insole condition) and that this was well maintained after wear. This was supported by mechanical tests conducted on the insoles. It was concluded that the insoles are sufficiently durable for military use. The main user complaint was that water retention reduced the comfort of the insoles; however, insulation tests conducted with a foot manikin indicated that switching from the current-issue Saran insoles to the trial insoles would not increase the risk of recruits sustaining nonfreezing cold injuries to their feet.     

Feasibility of using polytetrafluoroethylene flexible implant tube for interstitial brachytherapy patients

PURPOSETo design the different Polytetrafluoroethylene (PTFE) based flexible implant tubes using an in-house developed device and to evaluate them for High dose rate (HDR) interstitial brachytherapy using computer tomography images.METHODS AND MATERIALSPTFE hollow tube having a 2 mm (6 French) outer diameter (OD) and 1.4 mm inner diameter (ID) was used to design in-house single and/or double leader flexible catheters for interstitial brachytherapy implant. An in-house Plastic Wire Drawing Plate (PWDP) machine was developed. Customization of PTFE hollow flexible implant tube (FIT) was done through PWDP. Different percentages of BaSO₄ (5%, 10%, & 15%) were added to Nylon 6 to make radiopaque button. Various quality assurance tests were performed with the PTFE tubes implanted in the brinjal (phantom) before using them on the patients. That is, coupling of brachytherapy machine transfer tube with flexible PTFE Tubes, CT scan artifacts, tube kinks, breast template, and free-hand compatibility.RESULTSWith the help of the PWDP machine, plastic wires of different lengths were made for single leader and double leader tubes. The different plastic leader ends of 1 cm to 50 cm lengths having 1 mm diameter were created. The radiopaque button of Nylon 6 in circular shape having 1 cm diameter and 0.5 cm thick was created. Developed radiopaque buttons were visible on CT scan images as well as on radiograph images.CONCLUSIONSPTFE tubes of the desired length can be made depending upon the size of the brachytherapy implant and are inexpensive than commercially available flexible implant tubes.     

Uptake and dissolution of particulate iodipamide ethyl ester in the spleen. A morphologic study

Iodipamide ethyl ester (IDE) is an experimental particulate contrast agent being developed for CT image enhancement of the liver and spleen. IDE particles are phagocytized by the reticuloendothelial cells after an intravenous injection. The uptake and dissolution of IDE particles were studied in the spleen with light and electron microscopy. Two minutes after injection, intra- and extracellular IDE particles were found in the red pulp of the spleen. Highest concentration of IDE was seen in the marginal zone surrounding the white pulp. Particles also were seen elsewhere in the red pulp but only occasionally between the outermost cells of the white pulp. The extracellular particles disappeared within 4 hours postinjection. At one day postinjection, the amount of intracellular IDE particles had begun to decrease. Electron micrographs showed that the intracellular particles dissolved gradually in the phagocytes and caused transient degenerative morphologic changes. At three days postinjection, practically all IDE particles had disappeared from the spleen. Polystyrene latex particles were used as controls. They were phagocytized like the IDE particles, but they did not disappear from the phagocytes. IDE particles caused no morphologic injuries in nonphagocytic cells of the spleen.     

国产聚四氟乙烯膜对牙周膜细胞生长及实验性牙周组织再生的影响

通过对国产膨体聚四氟乙烯（e-PTFE)膜对牙周膜细胞（PDLC）生长以及对牙周组织再生（GTR）与牙周骨质再生的影响。探讨该膜的临床应用前景,结果发现PDLC可以在e-PTFE膜上良好的生长、膜对细胞无毒性及抑制作用。扫描电镜观察到细胞与膜附着紧密,在动物实验中,组织学观察发现e-PTFE膜特殊的孔隙结构对牙槽骨缺损的愈合有保护和促进的作用。如果膜的冠向边缘封闭得好,对结合上皮的根向迁移有一定的抑制作用,有利于新生牙槽骨及牙骨质的修复再生和新附着的建立,不失为一种前景看好的替代产品。