gamma-Interferon enhances the secretion of arachidonic acid metabolites from murine peritoneal macrophages stimulated with phorbol diesters

Macrophage activation in vivo has been associated with qualitative and quantitative alterations in the release and metabolism of arachidonic acid. In the present study, we examined the effect of in vitro macrophage activation with recombinant gamma-interferon (IFN-gamma) on arachidonic acid secretion induced by exposure to a variety of stimulating agents. Secretion stimulated by challenge with unopsonized zymosan, insoluble immune complexes, the calcium ionophore A23187, or combinations thereof was unaltered in IFN-gamma-treated macrophages. However, when phorbol diesters active as tumor promoters were employed as challenge agents, arachidonate secretion was enhanced as much as 10-fold over that seen in nonactivated controls. The enhanced secretory response to PMA was detectable as early as 1 hr after exposure to IFN-gamma, reached a maximum within 3 to 6 hr, and subsequently declined to control levels even in the continued presence of the agent. Treatment with IFN-gamma did not alter the pattern of individual metabolites produced by macrophages challenged with either zymosan or PMA. Finally, the sensitivity to phorbol diesters was also increased by treatment with IFN-gamma (ED50 reduced from 35 ng/ml to 4 ng/ml). Thus, IFN-gamma could prime macrophages for a substantially amplified response to phorbol esters. Because the cellular mediator of PMA action has been identified as a Ca++, phospholipid-dependent protein kinase, a role for this enzyme in macrophage functional development is indicated.     

Identification of a tumor inhibitory factor in rat ascites fluid

A polypeptide which inhibits the growth of human carcinoma cells has been characterized from Novikoff rat ascites fluid. This tumor inhibitory factor co-purified with transforming growth factor activity through acid/ethanol extraction and Bio-Gel chromatography. The two activities were completely separated by reverse phase HPLC. The tumor inhibitory factor is heat stable and requires disulfide bonds for bioactivity. This factor inhibited the anchorage independent growth of the more differentiated human colon carcinoma cell lines but did not affect the less differentiated carcinoma cells. The presence of stimulatory and inhibitory activities in the same extracts suggests that the relative concentrations of these factors may be important in the control of cell growth.     

Hominid divergence and speech evolution

Hominids evolved from a population which diverged from other hominoids during the Mio-Pliocene. This population was perhaps forced by ecological conditions and competitive exclusion to rely more on tools, gathering, hunting, vocal communication and memory, under whose mutually positively reinforcing effects the hominids diverged. The ape ancestors may have been forced into the forests (or they may have forced hominids onto the savanna), while hominids adapted to a plains, hunting econiche.Speech was selected for because verbal symbols served as retrieval cues for a large number of complex concepts and were transmissible, and thus could be used to influence food-getting and other behavior by the social group.Speech is dependent on three inherited entities: (1) anatomical and neurological adaptations which allow vocalization of a wide range of phonemes in rapid succession and which allow for (2) duality of patterning, thereby promoting a large number of words, and (3) encoding, which greatly increases the rate at which verbal information transfer can occur. Speech may have evolved through small hominid groups using progressively more phonemes in an increasingly blended manner, with encoding subsequently being selected for. Neandertals apparently could not encode speech and could speak only a restricted range of phonemes. Their expanded cranial capacity may have been selected for to store ambiguous and slowly transmitted verbal data.     

Relationship of Aflatoxicosis to Salmonella gallinarum Infections of Chickens

Aflatoxicosis and Salmonella gallinarum exert their effects on the body weight and mortality of chickens without any interaction.     

Observations on the vacuolar structure of the human syncytiotrophoblast

Summary The literature on the vacuolar structure of the human syncytiotrophoblast is briefly reviewed. Personal observations based on light and electron microscopic investigations are described and illustrated. The nature of the different kinds of syncytial vacuolation is discussed. In particular dilated vacuoles, which may be very large indeed, receive special attention; situated adjacent to the syncytial nuclei they have been called juxtanuclear vacuoles. They are directly continuous with the perinuclear spaces, and often receive tubular communications from the endoplasmic reticular system. The possible functional role of the syncytial vacuolar system is discussed in the light of the authors' findings and the related literature.Dedicated to Professor Dr. Kurt Goerttler on the occasion of his seventieth birthday.