药用矿物蒙脱石的X-射线定向衍射分析

目的：揭示蒙脱石层状晶体结构及层间吸附和膨胀性能,为其作为药物和药剂辅料提供科学依据。方法：将样品提纯,获得粒径小于1μm的胶体,制成取向样品,进行X－射线定向衍射分析。结果：得到了有关蒙脱石层间域在不同条件下的变化规律。结论：蒙脱石的层间吸附是可能的,而且定向衍射方法可以定量测定其层间距离。     

Integrin alpha4beta1 (VLA-4) expression and activity in retinal and peripheral neurons

The integrin alpha4beta1 fulfills important roles in inflammation and hematopoesis, but its functions in neurons are not well understood. Here we show that the alpha4 subunit is expressed on mouse retinal ganglion cells (RGCs) and undifferentiated retinal neuroblasts during the period of axon extension and migration. To determine if alpha4 integrins expressed by retinal neurons were active, neurons were cultured on known alpha4 ligands in vitro. Recombinant soluble vascular cell adhesion molecule 1 (rsVCAM-1), fibronectin, and osteopontin (OPN) induced neurite outgrowth that was diminished by function blocking antibodies specific for alpha4. Neurite outgrowth on OPN was also blocked by antibodies to the integrin beta1 subunit, implicating the alpha4beta1 heterodimer as one integrin receptor mediating outgrowth on OPN. OPN immunoreactivity was detected in the RGC fiber layer and optic nerve, suggesting that it may act as an alpha4 ligand in vivo. Neurons from chick lumbar sympathetic ganglia, chick dorsal root ganglia, and mouse superior cervical ganglia also extended neurites on rsVCAM-1, suggesting that integrin alpha4beta1 may play a role in the development of multiple neuronal cell types.     

Spontaneous regression: a hidden treasure buried in time.

Spontaneous tumor regression is a phenomenon that has been observed for hundreds, if not thousands of years. Although the term spontaneous implies 'without apparent cause', a review of case reports over the last several hundred years demonstrates that regression generally coincides with acute infections. Observations of this non-specific effect led to the emergence of active cancer immunotherapies by the 1700s. By the 1890s, William Coley refined this approach with a bacterial vaccine which, when administered properly, could induce complete regression of extensive metastatic disease. Unfortunately, after Coley's death, his vaccine and technique fell into obscurity. Modern approaches to treatment have reduced the occurrence of spontaneous regressions. Aseptic techniques and antibiotics significantly reduce postoperative infections, while chemotherapy and radiation impair immune activation even when an infection does occur. More than a century after its inception, Coley's vaccine and aggressive approach to treatment may still be one of most effective immunotherapies for cancer.     

Measurement of regional cerebral blood flow using ultrafast computed tomography. Theoretical aspects

Theoretical and practical limitations have prevented the measurement of regional cerebral blood flow using dynamic x-ray computed tomography. Development of the ultrafast computed tomography scanner has made it possible to overcome the practical limitations and measure changes in contrast concentration in the brain with excellent time and spatial resolution. By applying modifications of indicator dilution theory, we have derived a method to use these changes in contrast concentration determined using ultrafast computed tomography to measure the fractional vascular volume, mean transit time of blood, and blood flow within specific regions of the brain in a relatively simple and practical manner. This method could theoretically be used in the evaluation of physiological and pathophysiological alterations in cerebral blood flow.     

Our Postpandemic World: What Will It Take to Build a Better Future for People and Planet?

Policy Points

• Despite the pandemic''s ongoing devastating impacts, it also offers the opportunity and lessons for building a better, fairer, and sustainable world.
• Transformational change will require new ways of working, challenging powerful individuals and industries who worsened the crisis, will act to exploit it for personal gain, and will work to ensure that the future aligns with their interests.
• A flourishing world needs strong and equitable structures and systems, including strengthened democratic, research, and educational institutions, supported by ideas and discourses that are free of opaque and conflicted influence and that challenge the status quo and inequitable distribution of power.