Macrophage activation for tumor cytotoxicity: Control of cytotoxic activity by the time interval effector and target cells are exposed to lymphokines

Macrophages continuously exposed to lymphokines (LK) and target cells throughout a 48-hr cytotoxicity assay exhibit 3-fold more tumoricidal activity than do cells optimally treated with LK before addition of tumor cells. Increased cytotoxic activity induced by continuous LK treatment was not due to direct toxic effects of LK on tumor target cells or to alterations in target cell susceptibility to cytopathic effects of LK-activated macrophages. Moreover, sensitivities of responsive macrophages to LK activation signals and time courses for onset and loss of tumoricidal activity during continuous exposure or LK pulse were identical. Analysis of macrophage or LK dose responses and time courses for development of cytotoxicity each suggest that differences in tumoricidal activity between macrophages continuously exposed or pulsed with LK were quantitative: the number of cytotoxic events was increased 2.7 ± 0.2-fold (mean ± SEM for 11 experiments) during continuous LK treatment. Optimal levels of macrophage tumoricidal activity then occur only if effector cells, target cells and activation stimuli are simultaneously present for a defined time interval: tumor cells need not be present during the initial 2 to 3 hr of culture; LK can be removed after 8 hr with little or no loss of cytotoxic activity. However, removal of LK or target cells during the critical 4- to 8-hr interval decreased levels of cytotoxicity 3-fold. Thus, nonspecific effector function by LK-activated macrophages in controlled by both the physicochemical nature of the LK mediator and the time interval effector and target cells are exposed to LK.     

Healing and the Human Condition: Scenes from the Present Moment in Navajoland

The encounter of Navajo spirituality and healing practice with modernity in the present moment must be understood within an existential appreciation of temporality, tradition, domination, and immediacy. Examining the practical exigencies and experiential nuances in a performance of the Navajo Nightway ceremony allows us to elaborate this insight.     

造礁石珊瑚群落结构研究的概况,问题和前景

造礁石珊瑚作为珊瑚礁生态系统中的关键生物类群,其群落结构是珊瑚礁系统研究中的一个重 要方面。本文回顾了20余年以来世界各国对造礁石珊瑚群落结构研究所取得的主要进展和认识,指出了目前研究中存在的问题并分析了不同空间范围研究结论之间的缺乏一致性和中等干扰假说的不足。 最后,结合珊瑚礁生态系统基础理论和应用发展的需求,本文探讨了造礁石珊瑚群落结构研究的前景。     

中国鹤类现状及其保护对策

中国有9种鹤类,其中灰鹤（Grus grus）、黑颈鹤（Grus nigricollis）、丹顶鹤（Grus japonensis）、白枕鹤（Grus vipio）、赤颈鹤（Grus antigone）、蓑羽鹤（Anthropoides virgo）在中国进行繁殖。中国政府为保护鹤类采取了大量有效措施。本文在结合当前鹤类数量和保护现状的基础上,对中国鹤类的保护对策进行探讨。     

The relationship between dietary intake and the number of teeth in elderly Japanese subjects

Objective: This study used a precise weighing method to assess whether tooth loss was related to nutrient intake in elderly Japanese subjects. Material and methods: Fifty‐seven subjects aged 74 years were randomly selected from a longitudinal interdisciplinary study of ageing. Complete 3‐day food intake data were obtained by a precise weighing method. The dietary intakes of energy and nutrients were calculated based on the Standard Tables of Food Composition in Japan (5th ed.). A clinical evaluation of the number of teeth present was carried out. Multiple regression standardised coefficients for each nutrient was estimated based on a continuous scale adjusted for gender, smoking habits, and educational level. After dividing the subjects into two groups according to the number of teeth present (0–19, 20+), the difference in the intake of nutrients and the amount of food consumed per day was evaluated. Results: The number of teeth present had a significant relationship with the intake of several nutrients. In particular, total protein, animal protein, sodium, vitamin D, vitamin B₁, vitamin B₆, niacin, and pantothenic acid were significantly associated with the number of teeth present and with the two groups (0–19, 20+). The intake of vegetables and fish, shellfish, and their products was significantly lower among subjects with fewer teeth. Conclusion: This study suggests that there was a significant relationship between nutrient intake, such as minerals and vitamins from food, and tooth loss.     

Lordosis: Inhibiting effects of progesterone in the female rat

Progesterone has two types of inhibitory effects on female sexual behavior that have been well-documented in the guinea pig. The first occurs when high levels of progesterone are present around the start of the estrogen-priming process (“concurrent inhibition”). The second occurs immediately after the display of an estrogen-progesterone-induced period of estrous behavior (“sequential inhibition”). In the present set of experiments, we show that the rat, like the guinea pig, is capable of exhibiting both of these inhibitory effects of progesterone. However, rats require higher doses of progesterone than guinea pigs, at least for concurrent inhibition to be evident. In addition, we show that the dose of progesterone required in a single injection to produce concurrent inhibition is higher than the dose required to produce sequential inhibition in rats. A theory of how progesterone may be accomplishing its inhibitory effects on female sexual behavior in rodents is presented.