FD-1冷冻干燥机的研制及生物材料的冷冻干燥

观察自制冷冻干燥机冷冻干燥生物材料的效果。采用 R5 0 2压缩机和制冷剂制成 FD- 1冷冻干燥机。本实验冷冻干燥了胶原海绵、菌种及去纤酶。在冻干箱负载或空载情况下蒸发冷凝器温度均可达到 - 4 5℃ ,小冰箱可达到 - 30℃ ,冻干的胶原海绵具有许多孔洞的结构 ,冻干的菌种和去纤酶性能保持良好。 FD- 1冷冻干燥机适用于生物样品中小批量的冷冻干燥     

The effects of age and strain on aggression in male rats

Aggressive behaviors were compared for male Fischer-344 and Long-Evans rats formed into mixed-sex colonies at 100, 200, or 300 days of age. Within each strain, male aggression did not differ across these ages, nor did it differ for an additional group of 600-day old Long-Evans males: both the form and the incidence of specific aggressive and defensive behaviors remained relatively constant over an age range representing nearly the entire normal life span for this species. However, Fischer-344 males at all ages were reliably lower in aggression than the Long-Evans rats. The specific aggression components seen in the Fischer-344 rats tended to be nondamaging, resembling “play fighting” more than the tissue damaging attack behaviors typical of other strains. Despite the frequent use of this strain in gerontological research, such low levels of aggressiveness counterindicate their use in research in aging and aggression.     

A Strain Device Imposing Dynamic and Uniform Equi-Biaxial Strain to Cultured Cells

The objective of this study is to design a new apparatus to allow the control of the magnitude and frequency of dynamic stretch applied uniformly to cells cultured on a silicon elastic membrane. The apparatus is designed to produce equi-biaxial dynamic stretches with area changes ranging from 0% to 55% and frequencies ranging from 0 to 2 Hz. Homogeneous finite strain analysis using triangles of markers was performed to compute the symmetric two-dimensional Lagrangian strain tensor on the membrane. Measurements of strain in both static and dynamic conditions showed that the shear component of the strain tensor (E_rc) was near zero, and that there was no significant difference between radial (E_rr) and circumferential (E_cc) components, indicating the attainment of equi-biaxial strain. Bovine aortic endothelial cells were transiently transfected with a chimeric construct in which the luciferase reporter is driven by TPA-responsive elements (TRE). The transfected cells cultured on the membrane were stretched. The luciferase activity increased significantly only when the cells were stretched by 15% or more in area. Cells in different locations of the membrane showed similar induction of luciferase activities, confirming that strain is uniform and equi-biaxial across the membrane. © 1998 Biomedical Engineering Society. PAC98: 8780+s, 8745-k, 8722-q     

Linkage of human cytomegalovirus glycoprotein gO variant groups identified from worldwide clinical isolates with gN genotypes, implications for disease associations and evidence for N-terminal sites of positive selection

Previously, we identified the glycoprotein gO gene, UL74, as a hypervariable locus in the human cytomegalovirus (HCMV) genome [Virology 293 (2002) 281]. Here, we analyze gO from 50 isolates from congenitally infected newborns, transplant recipients, and HIV/AIDS patients from Italy, Australia, and UK. These are compared to four gO groups described from USA transplantation patients [J. Virol. 76 (2002) 10841]. Phylogenetic analyses identified seven genotypes. Divergence between genotypes was up to 55% and within 3%. Discrete linkage was shown between seven hypervariable gO and gN genotypes, but not with gB. This suggests interactions, while gN and gO are known to form complexes with distinct conserved glycoproteins gM, gH/gL, respectively, both are involved in fusogenic entry and exit. Codon-based maximum likelihood models showed evidence for sites of positive selection. Further analyses of disease relationships should take into account these newly defined gO/gN groups.     

应变率成像在胎儿房性心律失常诊断中应用的初步探讨

目的探讨应用速度向量成像（VVI）技术对胎儿房性心律失常时心肌结构力学及形变学影响的应变与应变率研究，评价胎儿心律失常时对心肌应激状态、运动传导就及功能的影像。方法对检出的77例胎儿心律失常（其中室上性心动过速（SVT）12例、65例为频发性房性早搏（PAC））进行VVI成像技术分析，检测心律失常时胎儿心肌运动速度向量变化及对应变与应变率影响，对照组80例心率正常胎儿。结果胎儿SVT12例中7例持续发作48h者治疗前心室率250—310bpm，均合并心衰及出现水肿，VVI速度向量振幅明显降低，其应变与应变率明显低于对照组（P〈0．01）；阵发一陛SVT5例VVI速度向量振幅-过性降低，心肌应变与应变率无变化；频发PAC组示早搏时速度向量振幅改变，且运动方向同步，心肌运动三维数据定量可显示旱搏及代偿间期的三维模式，应变与应变率与对照组无差异（P〉0．05）。结论VVI成像通过心律失常心肌结构力学变化解析胎儿心律失常，特别是对胎儿心动过速时的快速心率可进行实时动态分析。及应用M型扫描法确认心动周期使胎儿心肌应变与应变率分析成为可行。     

小鼠IgE抗体生成的免疫调节——对半抗原-载体蛋白质IgE抗体应答的研究

众所周知,半抗原具有两个特性:(1)无免疫原性;(2)具有反应原性。当半抗原与载体蛋白质结合后便可获得免疫原性,而成为完全抗原。在Ⅰ型变态反应实验动物研究中广为应     

Electrochemical release testing of nickel-titanium orthodontic wires in artificial saliva using thin layer activation

Alloys based on Ni–Ti intermetallics generally exhibit special shape memory and pseudoelastic properties, which make them desirable for use in the dental field as orthodontic wires. The possibility of nickel release from these materials is of high concern, because the allergenicity of this element. The aim of this study was to test pseudoelastic Ni–Ti wires in simulated physiological conditions, investigating the combined effect of strain and fluoridated media: the wires were examined both under strained (5% tensile strain) and unstrained conditions, in fluoridated artificial saliva at 37 °C. Real time electrochemical nickel release testing was performed using a novel application of a radiotracer based method, thin layer activation (TLA). TLA was validated, in unstrained conditions, against adsorptive stripping voltammetry methodology. Control tests were also performed in non-fluoridated artificial saliva. From our research it transpired that the corrosion behaviour of Ni–Ti alloy is highly affected by the fluoride content, showing a release of 4.79 ± 0.10 μg/cm²/day, but, differently from other biomaterials, it does not seem to be affected by elastic tensile strain. The application of the TLA method in the biomedical field appears a suitable technique to monitor in real time the corrosion behaviour of biomedical devices.     

Effects of sex and estrous cycle on modulation of the acoustic startle response in mice

Potential sex differences in amplitude, habituation, prepulse inhibition (PPI) and prepulse facilitation (PPF) of the acoustic startle response (ASR) were investigated using male and female mice from the two different inbred mouse strains C57BL/6J (C57) and C3H. Furthermore, the effects of the estrous cycle were tested. The estrous cycle appeared to have no effect on ASR amplitude, habituation, PPF and PPI, the latter being in contrast to results in rats and humans. While sex had no effect on PPI or PPF, males exhibited higher startle amplitudes than females, irrespective of strain, which we discuss to be due to increased male anxiety. In addition, long-term habituation was stronger in C57 males and short-term habituation was weaker in C3H males with respect to females. These results provide evidence for influence of the reproductive hormones on startle reactivity and startle habituation; we therefore conclude that future studies involving genetic influences on behavior using inbred strains are only complete if both sexes are included.     

A strain gauge device for measuring feeding or drinking in laboratory rats

The details of mechanical construction and electronic circuitry of a strain gauge system for continuously measuring food and water ingestion in laboratory rats are described. The system has been reliably tested over a number of years. It is eminently suitable for investigating daily rhythms in rat feeding and drinking behavior, where a large volume of data is collected over extended periods of time.     

Teratological studies on the TCDD congener 3,3′,4,4′-tetrachloroazoxybenzene in sensitive and nonsensitive mouse strains: Evidence for direct effect on embryonic tissues

The teratogenicity of 3,3,4,4-tetrachloroazoxybenzene (TCAOB), a TCDD congener, was studied in Ah-responsive (C57BL and NMRI) and non-responsive (DBA/2J and AKR/NBom) strains of mice. In the responsive strains, the TCAOB produced cleft palate and hydronephrosis in 50–90% of the offspring at a dose level of 6–8 mg/kg b.w. in the absence of apparent maternal toxicity. Day 11 was shown to be the day of highest sensitivity (palatal closure occurs at day 14) in the C57BL strain. Higher doses (16 mg/kg b.w.) produced high rate of fetal death both in responsive (C57BL; 60%) and non-responsive (DBA; 40%) strains. These doses induced cleft palate in 95% of the surviving C57BL fetuses but failed to do so in the DBA strain. The non-sensitivity of the DBA and AKR strains appeared to segregate as a dominant trait. Backcrosses between NMRI x DBA F₁ generation and NMRI showed an intermediate sensitivity. It was shown that the genotype of the embryo was of ultimate importance for the development of cleft palate. There appeared however to be an additional host (maternal) factor as well, because the offspring of NMRI females mated with NMRI x DBA F₁ males showed a higher rate of cleft palate as compared to those of the crossing between NMRI x DBA F₁ females and NMRI males. Light and scanning electron microscopy indicated that the apical epithelial cells of the secondary palates failed to follow the normal pattern of programmed cell death, suggesting a similar mechanism of pathogenesis as previously described for TCDD.