Exercise,Lymphokines, Calories,and Cancer

In brief: Epidemiological studies suggest that exercise reduces the risk of cancer. The leading studies are reviewed here, along with the underlying animal research and the plausible protective mechanisms in humans. The conclusion, based on the literature, is that exercise may help defend against cancer by Preventing obesity, stimulating lymphokines, and/or facilitating other healthful changes in behavior. However, the data are largely preliminary and controversial. Thus, although there is reason to believe that exercise helps prevent cancer, much more research is needed to prove that it does. This article is the first in a series on internal medicine.     

The effects of TTS-scopolamine, dimenhydrinate, lidocaine, and tocainide on motion sickness, vertigo, and nystagmus

The effects of TTS-scopolamine, dimenhydrinate, lidocaine, and tocainide on motion sickness and vertigo and on caloric and postrotatory nystagmus were evaluated in healthy volunteers. TTS-scopolamine was administered transdermally (delivering approximately 10 micrograms X h-1 scopolamine base) and 100 mg dimenhydrinate orally. Lidocaine and tocainide were administered intravenously (average plasma concentration of lidocaine 6 mol X L-1 and of tocainide 20 mol X L-1). TTS-scopolamine and dimenhydrinate significantly reduced vertigo induced by calorization of the ears, nausea provoked with Coriolis maneuvre, and nystagmus in caloric and rotatory tests. During treatment with lidocaine and tocainide no alleviation of vertigo and nausea was observed. Caloric nystagmus was reduced but rotation induced nystagmus was virtually unchanged. Presumably the motion sickness drugs act at the brain stem where TTS-scopolamine and dimenhydrinate have their target cells in the vestibular nuclei. Furthermore, the alleviation of motion sickness was linked to a decline of nystagmus. Lidocaine and tocainide, the action of which in vertigo and nausea in patients is proposed to be on the vestibular end organs and the supratentorial brain structures, consistently failed to alleviate motion sickness.     

Contrast, coagulation, and fibrinolysis

Some adverse clinical effects of intravascular radiologic contrast agents have been attributed to their interference with the normal hemostatic processes. This study compares the effects of the low osmolality agents with those of the conventional agents by in vitro studies of platelet function, fibrin formation, and fibrinolytic activation. In various degrees, all the contrast agents studied inhibit platelet aggregation and fibrin formation but show virtually no direct activation of fibrinolysis. The new low osmolality agents generally show lesser inhibitory effects on the hemostatic mechanisms. Some clinical implications are discussed.     

Stress, catecholamines, and sleep

Difficulties in defining stress stem from its subjective nature. Measurements of stress based on its effects on physical and mental morbidity tend to be speculative because of the multifactorial causation of stress-related diseases, and the characteristically long time-lag between stress states and morbidity. In this study catecholamine output was measured in a group of adults Oxfordshire villagers and the observed variations were related to their lifestyles and health perceptions. A marked circadian variation was observed with adrenaline showing the most marked associations with lifestyle. In men it was possible to account for a relatively high proportion of the variation in adrenaline excretion by relating values to certain factors associated with stress. In women there appears to be a similar association between adrenaline output and the social class of the husband. Data were also obtained on sleep characteristics, which were assessed with regard to lifestyle. Very broadly, sleep duration is related to the level of waking activity, while sleep latency and quality are correlated with people's self-perception of health.