Screen for type-C ribonucleic acid viruses in vaccines using the ribonucleic acid-dependent deoxyribonucleic acid polymerase assay.

The ribonucleic acid-dependent deoxyribonucleic acid polymerase assay was used to detect type-C viruses in live virus vaccines. Conditions were first established to maximize the sensitivity of the assay. Vaccines tested included live poliomyelitis, rubella, measles, mumps, and yellow fever. Only yellow fever and measles vaccines known to have been produced in avian leukosis-contaminated cells showed evidence of type-C viruses using the assay. The result of the survey show that the assay has direct practical application to the problem of detecting latent agents in biological products intended for human use.     

Wall thickness and constrictive responses of the caudal artery in rats with renovascular hypertension

In rats with hypertension modeled by the one kidney-one clamp method, constrictory responses of the isolated caudal artery to norepinephrine differed under various perfusion conditions. Vascular reactions in hypertensive rats were more potent at a constant flow rate, and less potent at a constant pressure compared to those in normotensive rats. Previous experiments demonstrated similar changes in constrictory responses of the caudal artery in spontaneously hypertensive rats. It is assumed that these peculiarities of the vascular reactivity during hypertension are determined by thickening of the smooth muscle layer of the vascular wall. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 159–162, August, 2000     

Wall thickness and constrictive responses of the caudal artery in rats with renovascular hypertension

In rats with hypertension modeled by the one kidney-one clamp method, constrictory responses of the isolated caudal artery to norepinephrine differed under various perfusion conditions. Vascular reactions in hypertensive rats were more potent at a constant flow rate, and less potent at a constant pressure compared to those in normotensive rats. Previous experiments demonstrated similar changes in constrictory responses of the caudal artery in spontaneously hypertensive rats. It is assumed that these peculiarities of the vascular reactivity during hypertension are determined by thickening of the smooth muscle layer of the vascular wall. Translated fromByulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 159–162, August, 2000     

Compensator thickness verification using an a-Si EPID

Electronic portal imaging devices (EPIDs) are being increasingly employed to make therapy verification and dose measurements in the clinic. In this work, we investigate the use of an amorphous silicon (a-Si) EPID to verify the accuracy of compensator fabrication and mounting. Compensator thickness estimates on a two-dimensional grid were calculated from the primary component of transmission obtained by subtracting a modeled scatter component from the total transmission measured with the EPID. The primary component was related to the thickness via an exponential relation that includes beam hardening. Implementation of the method involved determination of: (i) a calibration curve relating EPID pixel values to energy fluence for open and attenuated fields, which was found to be linear for open fields but to have a small quadratic component for attenuated beams; (ii) EPID scatter factors to account for field size effects, which exhibited a small dependence on compensator thickness and field size; (iii) the attenuation coefficient of the steel shot compensator material, which varied slightly with off-axis distance and field size, and (iv) an analytical model to predict scatter from the compensator, which was calculated to be <4% at the standard EPID imaging distance of 140 cm. Thickness distributions were then measured for several types of attenuators including flat, test, and clinical compensators. Although uncertainties associated with compensator manufacturing were non-negligible and made assessment of thickness measurement uncertainty difficult, we estimate the latter to be approximately 0.5 mm for steel shot compensators of thickness <4 cm.     

Detection of simian type-C particles in Mason-Pfizer virus infected cultures.

A simian type-C virus has been detected in cultures chronically infected with Mason-Pfizer monkey virus (M-PMV). Simultaneous budding of M-PMV and type-C virus particles from the same cells was observed in cultures incubated at 37 or 40 degrees C. However, the frequency of such cells was greater in cultures grown at 40 degrees C. Although clusters of type-C viral buds were seen at the surface of the cells, extracellular mature type-C particles in cell pellets or concentrated virus preparations were very rarely found. The increase in frequency of type-C buds was found to be transitory since cultures adapted to growing at the high temperature demonstrated budding type-C particles only occasionally. Cultures producing type-C buds were found to contain, in addition to M-PMV antigens, serological activity with polyvalent antisera produced against multiple structural components of endogenous baboon virus (BV) or simian sarcoma virus (SiSV). The reactivity, however, was found not to be serologically related to the major SiSV P28 core protein.     

Use of commercially prepared control sera as quality control materials for spectrophotometric bilirubin determinations in amniotic fluid

The visible absorption spectra of dilutions of commercially prepared chemistry control sera closely mimic those of jaundiced amniotic fluids in cases of fetal rhesus isoimmunization. The authors have assessed the use of these materials for the quality control of net absorbance measurements at 450 nm on amniotic fluids. The authors conclude that they are excellent quality control materials because of their ready availability, low cost, long-term stability, wide range of bilirubin concentrations, and their close resemblance to jaundiced amniotic fluids with respect to light absorption and scattering, sensitivity to light, and pigment extractability into chloroform. Their spectra also contain a maximum at 410 nm, so these materials can also be used as controls for net absorbance measurements at 410 nm, a determination that indicates the extent of heme or meconium pigment interference with net absorbance measurements at 450 nm. These materials both supplement and complement the requisite spectrophotometric performance checks of wavelength calibration and photometric accuracy.     

Label-free measurement of microbicidal gel thickness using low-coherence interferometry

Spectral-domain low-coherence interferometry (LCI) was used to measure the thickness of microbicidal gels applied to a cylindrical calibration test socket. Microbicides are topical formulations containing active ingredients targeted to inhibit specific pathogens that are currently under development for application to the epithelial lining of the lower female reproductive tract to combat sexually transmitted infections such as HIV. Understanding the deployment and drug delivery of these formulations is vital to maximizing their effectiveness. Previously, in vivo measurements of microbicidal formulation thickness were assessed using fluorescence measurements of fluorescein-labeled gels via an optical endoscope-based device. Here we present an LCI-based device that measures the thickness of a formulation without the use of any exogenous agents by analyzing the interference pattern generated between the reflections from the front and back surface of the sample. Results are presented that validate the effectiveness and performance of the LCI measurement in a clinically relevant system as compared to an existing fluorescence-based method. The impact of the new LCI-based design on in vivo measurements is discussed.     

An analysis of type-C retrovirus polypeptides and their associations in the virion.

The polypeptide compositions of [³H]leucine-labeled Prague-Rous sarcoma virus-subgroup C (Pr-RSV-C) and Friend murine leukemia virus (FLV) were investigated using guanidine hydrochloride gel filtration and a high-resolution SDS-polyacrylamide-gel system. These techniques resolved seven major structural components in Pr-RSV-C (gp85, gp35, p27, p19, p12, p15, and p10), as reported previously for other avian leukosis-sarcoma viruses. However, in the case of FLV two previously unresolved proteins (p15E and p12E) were clearly demonstrated in addition to gp71, p30, p15C, p12, and p10. FLV p15E, p12E, and gp71 were removed when intact virions were digested with bromelain, whereas the remaining components were not affected. These and other studies support the notion that gp71, p15E, and p12E are situated on the surface of the virion. The linkages (covalent and noncovalent) between viral polypeptides were also examined. The results of these studies indicate that more than 90% of avian gp85 and gp35 are disulfide linked as a viral glycoprotein complex (VGP). The data also suggests that p19 exists as a network of disulfide-linked molecules, some of which may be further linked to VGP. In contrast to the avian system, only about 10–15% of FLV gp71 is disulfide linked to p15E in the VGP complex; the remaining gp71 is apparently loosely attached to the virus, perhaps by a noncovalent interaction with p12E. The implications of these associations to virus structure and assembly are discussed.     

Signal transmission in the catfish retina. III. Transmission to type-C cell

Current injected into horizontal-cell somas and axons produced transient (on-off) depolarizations from type-C cells (commonly known as transient amacrine cells) similar to those produced by light. Both the light- and current-induced responses had very small linear components and nonlinear components as represented by the second-order kernels, which reproduced the cell's response with a reasonable degree of accuracy. The second-order kernels were well defined and stereotyped. The quadratic nature of the nonlinear component is reflected in the frequency doubling response as well as the very steep input-output relationship of the cell. Type-C cell's responses evoked by light and current differed in a subtle but distinct fashion, and this difference appeared in the signature of the second-order kernels. The light-produced kernels had two diagonal positive peaks and off-diagonal valleys ("four-eye" structure), whereas the current-produced kernels had a single on-diagonal positive peak with off-diagonal negative valleys ("three-eye" structure). The difference in the kernel configuration was reflected in the cell's step-evoked response. Some type-C cells produced faster responses whereas others produced slower responses, whether evoked by light or by current. Our past and present results show that type-C cells produce a very nonlinear response that is not necessarily complex.     

新型肝脏管道模型的数字化制造研究

目的　设计并制作内部管道与肝实质外形兼备的新型肝脏管道模型。  方法　选取一具新鲜的人体肝脏标本,肝静脉及门静脉灌注后行64排螺旋CT扫描,利用Mimics软件重建门静脉、肝静脉及肝实质三维模型。在Magic4.0软件中设计肝脏管道与肝实质外壳模具的装配结构。将设计好的模型通过快速成型机进行模型的三维打印,并进行组装形成管道铸模模具。将融化的透明果冻蜡注入铸模模具内,待蜡凝固后,除去肝实质壳模具,获得新型肝脏管道模型。  结果　本研究通过三维重建、快速成型及模具技术成功地制作了内部管道与肝实质外形兼备的新型肝脏管道模型。模型清晰地显示肝内管道的分布情况,位置关系,分支关系,管道直径等,快速成型管道的最小直径约为1.2 mm。由透明果冻蜡制作的肝实质外形良好,清晰透明,质地与肝实质相近。   结论　新型肝脏管道模型表现力丰富,容易保存。它拓展了铸型标本在医学教育,科研,临床上的应用。     

Development of an in vivo tissue-engineered vascular graft with designed wall thickness (biotube type C) based on a novel caged mold

Small-diameter biotube vascular grafts developed by in-body tissue architecture had high patency at implantation into rabbit carotid arteries or rat abdominal aortas. However, the thin walls (34 ± 14 μm) of the original biotubes made their implantation difficult into areas with low blood flow volumes or low blood pressure due to insufficient mechanical strength to maintain luminal shape. In this study, caged molds with several windows were designed to prepare more robust biotubes. The molds were assembled with silicone tubes (external diameter 2 mm) and cylindrical covers (outer diameter 7 mm) with 12 linear windows (1 × 9 mm). After the molds were embedded into beagle dorsal subcutaneous pouches for 4 weeks, type C (cage) biotubes were obtained by completely extracting the surrounding connective tissues from the molds and removing the molds. The biotube walls (778 ± 31 μm) were formed at the aperture (width 1 mm) between the silicone rods and the covers by connective cell migration through the windows of the covers. Excellent mechanical properties (external pressure resistance, approximately 4 times higher than beagle native femoral arteries; burst strength, approximately 2 times higher than original biotubes) were obtained. In the acute phase of implantation of the biotubes into beagle femoral arteries, perfect patency was obtained with little stenosis and no aneurysmal dilation. The type C biotubes may be useful for implantation into peripheral arteries or veins in addition to aortas.     

Biocompatibility of dense hydroxyapatite prepared using an SPS process

In the present study, the preparation of dense hydroxyapatite (HAp) materials at relative low temperatures using a spark plasma sintering was carried out. The bioactivity of HAp samples prepared by a spark plasma sintering method was investigated by in vitro tests and compared with HAp obtained by a conventional hot-pressing method. No growth of bone-like HAp crystals on surface of HAp sintered by a conventional hot-pressing method at 1200 degrees C was observed after immersion in a simulated body fluid (SBF) for 2 days. However, many large bone-like HAp crystals were observed on the surface of HAp samples prepared by a spark plasma sintering at 1200 degrees C after 2 days in the SBF immersion test. Especially, the negatively charged surface of the HAp samples prepared by spark plasma sintering was covered with larger HAp crystals compared with the positively charged surface. The electric poling of HAp was measured using a thermally simulated current technique. This rapid growth of bone-like HAp crystals of the HAp samples made by spark plasma sintering was believed to be related with the OH(-) and/or Ca(2(+) ) ion deficiency at the grain boundaries of the HAp matrix grains as well as a small electric poling effect resulting during the spark plasma sintering process.     

High efficiency light-induced dielectrophoresis biochip prepared using CVD techniques

This article describes a high-efficiency light-induced dielectrophoresis biochip containing a thin film prepared through inductively coupled plasma chemical vapor deposition (ICPCVD). The biochip comprises two ITO glass substrates and a photoconductive amorphous silicon thin film. The biochip can effectively sort particular particles (or cells) by projecting visible light onto the surface of the silicon thin film. The sorting efficiency of biochips is highly associated with the quality of the deposited amorphous silicon thin films; therefore, the choice of deposition technique is extremely critical. However, no study has examined this problem. Hence, the current study thoroughly compared the efficiency of the biochip when films produced through plasma-enhanced chemical vapor deposition and ICPCVD are used.     

偏头痛患者脉络膜厚度改变的系统评价

目的 系统评价偏头痛患者脉络膜厚度的改变。方法 检索从建库到2020年1月1日期间,PubMed、EMbase、Scopus、中国生物医学文献数据库、中国知网、维普数据库、万方数据库收录的关于相干光断层扫描评估偏头痛的研究。两名研究者独立筛选、提取和评价纳入的研究,采用 Stata 14.0 软件进行 Meta 分析。结果 共纳入12 项病例对照研究,共1 091名研究对象,其中偏头痛组646例,对照组445例。偏头痛组及对照组间的各指标观察结果均有统计学异质性(P值均<0.10),均采用随机效应模型进行分析。Meta分析显示,偏头痛组黄斑中心凹脉络膜厚度及距中心凹鼻侧1.0 mm处、鼻侧2.0 mm处、颞侧1.0 mm处、颞侧2.0 mm处的脉络膜厚度均比对照组低,其加权均数差值(95%可信区间)分别为-39.97 μm(-54.43~ -25.50 μm)、-41.60 μm (-57.74~ -25.45 μm)、-41.95 μm (-59.59~ -24.31 μm)、-44.32 μm (-63.31~ -25.34 μm)、-39.51 μm (-59.25~ -19.77 μm),差异均有统计学意义(P值均<0.01)。亚组分析显示,有先兆偏头痛和无先兆偏头痛患者各位点脉络膜厚度的差异均无统计学意义(P值均>0.05)。Begg's检验和Egger's 检验的P值分别为0.156和0.484,无发表偏倚的证据。结论 偏头痛患者的脉络膜变薄,脉络膜厚度改变可能是偏头痛发病的重要指标之一,是偏头痛诊断的一个重要依据。需要进一步研究以明确不同类型偏头痛的脉络膜厚度改变程度。     

Molecular weight control of linear polyethylenes prepared in gas phase with Ziegler catalysts

Linear polyethylenes covering the range from high to low density were prepared in gas phase using an MgCl₂-supported Ziegler catalyst deposited on silica (bisupported catalyst). The comonomer used was 1-butene. Molecular weights are dependent both on 1-butene concentration and hydrogen pressure. The interaction of these two factors can be interpreted by the enhancement of the transfer reactions after 1-butene insertion.     

结构性植骨重建髋臼上外侧壁骨缺损的疗效

目的:探讨结构性植骨重建髋臼上外侧壁骨缺损的疗效。方法:患者共59例61髋,自体骨植骨43髋、异体骨植骨15髋、自体骨与异体骨混合植骨3髋。骨缺损最大62mm×33mm×26mm,最小31mm×19mm×18mm,平均41mm×23mm×21mm。全部采用非骨水泥髋臼假体。临床评价采用Harris评分,X线观察移植骨愈合和髋臼假体的稳定情况等。结果:平均随访时间为10.1a,本组Harris评分平均从61分提高到89分,所有病例髋臼假体稳定,移植骨愈合。X线片显示移植骨愈合时间平均为6.9个月,出现移植骨轻度和中度吸收18髋,对髋臼假体的覆盖和稳定性无明显影响。本组术后翻修6髋,其原因为骨溶解2髋,聚乙烯髋臼衬垫磨损和脱位4髋。结论:采用自体骨、异体骨或混合骨进行结构性植骨重建髋臼上外侧壁骨缺损,经过中长期随访,移植骨全部愈合良好,获得满意的疗效;32.8%病例出现轻、中度的骨吸收,但对髋臼假体的稳定性无明显影响。