肿瘤干细胞研究进展及临床应用前景

肿瘤干细胞是肿瘤中具有自我更新能力和分化潜能,能产生异质性细胞的细胞。我们简要阐述了肿瘤干细胞存在的证据、分离技术及来源,并对以肿瘤干细胞为靶标的肿瘤治疗途径、临床应用前景和问题进行了综述。     

Studies on bacteria-like particles sampled from the stratosphere

Bacteria-like particles recovered from the stratosphere and deposited on cellulose acetate membranes have been analysed to confirm their bacterial nature. One particle appeared to be attached to an inorganic particle apparently by mucoid material typically produced by bacteria. A filamentous structure, morphologically similar to a fungal hypha, was also observed. EDS analysis showed that the particles were all non-mineral and therefore could be biological in nature. However, the composition of several clumps of nanobacteria-sized particles were found, by SIMS analysis, to be inconsistent with that of bacteria. The results show that it is dangerous to assume that bacteria-like particles seen under scanning electron microscopy are necessarily bacteria.     

Polyploid genome of <Emphasis Type="Italic">Camelina sativa</Emphasis>revealed by isolation of fatty acid synthesis genes

Background  

Camelina sativa, an oilseed crop in the Brassicaceae family, has inspired renewed interest due to its potential for biofuels applications. Little is understood of the nature of the C. sativa genome, however. A study was undertaken to characterize two genes in the fatty acid biosynthesis pathway, fatty acid desaturase (FAD) 2 and fatty acid elongase (FAE) 1, which revealed unexpected complexity in the C. sativa genome.     

Invasive aspergillosis in a "healthy" patient.

A case of invasive aspergillosis complicated by the formation of an aspergilloma is described. The patient, a 48-year-old man, was apparently healthy except for mild alcoholic steatosis of the liver. A review of the literature revealed that 5 of the 14 previously reported cases of invasive aspergillosis in seemingly immunocompetent hosts were associated with liver disease. Immunologic investigation in this case revealed transient cutaneous anergy during the acute illness and normal lymphocyte function. Assessment of polymorphonuclear leukocyte function, however, showed abnormalities of phagocytosis as well as impairment of intracellular bactericidal activity. These abnormalities may have contributed to a relative immunodeficiency. Impairment of immune function may play a role in the pathogenesis of invasive aspergillosis in some apparently healthy patients.     

一株石油降解菌培养基的优化

目的：有效降低石油降解菌株CT-6在工业生产中的培养成本,提高培养速度。方法：利用Minitab软件,采用中心组合设计、响应面分析,以葡萄糖、蔗糖、可溶性淀粉为碳源,以硝酸铵、尿素、氯化铵为氮源,对高效降解石油菌株CT-6的培养基进行了优化。结果：当碳源葡萄糖为5.6818g/L、氮源氯化铵为3.8030g/L时,菌株CT-6培养17h,OD600达到0.615。结论：优化前后,菌体CT-6的OD600分别为0.289和0.615,提高了112.8%,说明该培养基更有利于菌株CT-6的生长。     

Lead-phase and red-stripe color morphs of red-backed salamanders Plethodon cinereus differ in hematological stress indices: A consequence of differential predation pressure?

Throughout the animal kingdom there are species that have two or more phenotypic forms or 'morphs', and many of these are amphibians. In North America, the red-backed salamander Plethodon cinereus can have either a red dorsal stripe or no dorsal stripe (lead-phase form), and evidence to date indicates the lead-phase form incurs a greater number of attacks from predators. In a recent collection of 51 P. Cinereus, blood smears of both color morphs (35 red-stripe, 16 lead-phase) were examined to obtain numbers of circulating leukocytes (via light microscopy), which can be used to indirectly estimate levels of stress hormones in vertebrates via a 'hematological stress index', which is the ratio between the number of two leukocyte types (neutrophils and lymphoeytes). Our results showed that lead-phase salamanders tended to have greater numbers of circulating neutrophils and lower numbers of circulating iymphocytes than red-stripe morphs, leading to higher average neutrophil-lymphocyte ratios in lead-phase individuals. Since the salamanders were held (refrigerated) for 7 days before sampling, we cannot be certain if this effect is a stress reaction to the captivity or the normal level for this morph. However comparison with two sets of related salamanders that were captured and sampled immediately indicates the red-stripe salamanders were either not stressed from the captivity at all, or their white blood cell distributions had returned to normal after 7 days of captivity. Taken together, our results indicate that lead-phase forms of P. Cinereus have higher stress levels than the red-stripe forms, which may be a consequence of their higher exposure to, and/or attacks from, predators. They may also indicate that the lead-phase form is less-suited to captivity than the red-stripe form of this species.     

Studies on bacteria-like particles sampled from the stratosphere

Bacteria-like particles recovered from the stratosphere and deposited on cellulose acetate membranes have been analysed to confirm their bacterial nature. One particle appeared to be attached to an inorganic particle apparently by mucoid material typically produced by bacteria. A filamentous structure, morphologically similar to a fungal hypha, was also observed. EDS analysis showed that the particles were all non-mineral and therefore could be biological in nature. However, the composition of several clumps of nanobacteria-sized particles were found, by SIMS analysis, to be inconsistent with that of bacteria. The results show that it is dangerous to assume that bacteria-like particles seen under scanning electron microscopy are necessarily bacteria.