Benzene and the risk of non-Hodgkin lymphoma: A review and meta-analysis of the literature

Benzene, an accepted leukemogen, has been suggested to cause other hemato- and lymphopoietic cancers. Here we review the published literature for non-Hodgkin lymphoma (NHL) and occupational exposure to benzene. Six cohorts, sixteen case–control studies and two studies of other designs were identified through keyword searches of bibliographic databases. Twenty-two of twenty-four studies found no association between NHL and ever exposed to benzene compared to never; a random-effects meta-analysis gave a pooled risk estimate of 1.11 (95% confidence interval 0.94–1.30). Our finding of no effect agrees with one of two previous meta-analyses. The other meta-analysis examined if high benzene exposure increased NHL risk but a lack of consistent exposure categories within the same metric should have precluded pooling risks by exposure level. Instead, we reviewed whether dose–response relationships existed. The best available data came from six studies where exposure was estimated from historical measurements and on the whole, no trends in risks of NHL with rising cumulative, average, peak, or duration of benzene exposure were found. NHL is a heterogeneous group of malignancies and although less well-studied, benzene was not associated with any NHL subtype. In conclusion, benzene at either low or high doses does not increase the risk of NHL.     

Antibodies to Xenopus egg S6 kinase II recognize S6 kinase from progesterone- and insulin-stimulated Xenopus oocytes and from proliferating chicken embryo fibroblasts.

Ribosomal protein S6 becomes highly phosphorylated during progesterone- or insulin-induced maturation of Xenopus laevis oocytes. We have previously purified an Mr 92,000 protein as one of the major S6 kinases from Xenopus unfertilized eggs. In this paper we confirm by renaturation of activity from a sodium dodecyl sulfate-polyacrylamide gel that this protein is an S6 kinase. This enzyme, termed S6 kinase II (S6 K II), was used for the preparation of polyclonal antiserum. Immunocomplexes formed with the antiserum and purified S6 K II were able to express kinase activity with the same substrate specificity as that of the purified enzyme, including autophosphorylation of S6 K II itself. The antiserum did not react with S6 kinase I, another major S6 kinase present in Xenopus eggs, which is chromatographically distinct from S6 K II. The administration of progesterone to oocytes resulted in a 20- to 25-fold increase in S6 kinase activity in extracts of these cells. Immunocomplex kinase assays done on extracts revealed that anti-S6 K II serum reacted with S6 kinase from progesterone-treated oocytes. This antiserum also reacted with the activated S6 kinase from insulin-stimulated oocytes. In addition, anti-S6 K II serum reacted with activated S6 kinase from chicken embryo fibroblasts stimulated with serum or transformed by Rous sarcoma virus. These results indicate that S6 K II or an antigenically related S6 kinase(s) is subject to regulation by mitogenic stimuli in various cell types.     

Rapid repression of quiescence-specific gene expression by epidermal growth factor, insulin, and pp60v-src.

We isolated a cDNA for p20K, a secreted protein preferentially synthesized in nonproliferating cells. p20K mRNA and protein levels declined rapidly following treatment with various mitogens. DNA sequence analysis of the p20K cDNA predicted a novel protein distantly related to alpha 2 mu-globulin and plasma retinol-binding protein.     

Effects of Prolonged Depolarization on the Nicotinic Acetylcholine Receptors of PC12 Cells

To determine whether prolonged depolarization and/or changes in intracellular Ca2+ concentrations stimulate adaptive responses of neuronal nicotinic acetylcholine receptors, PC12 pheochromocytoma cells were grown in medium containing various concentrations of K+. Nicotinic receptor function was determined as carbachol-stimulated uptake of 86Rb+. Cells were exposed to 50 mM K+ for up to 4 days and then allowed to repolarize for 60 min. Under these conditions, no changes in basal or carbachol-stimulated uptake of 86Rb+ were observed. Furthermore, neither the time course of carbachol-stimulated uptake or the carbachol concentration dependence of 86Rb+ uptake was altered. Finally, concurrent depolarization did not affect the functional down-regulation produced by chronic exposure of the cells to carbachol. Thus, neuronal nicotinic acetylcholine receptors on PC12 cells do not appear to be regulated by depolarization or prolonged elevation of the intracellular Ca2+ level.     

Individuals and society in anthropological theory

Conclusion Though relatively little direct attention has been given by Marxist anthropologists to a theory of individual behavior and thought in relation to societal processes, the above partial summary indicates the wealth of insight that is available for elaborating such a theory. In addition, there are of course significant developments in the field of psychology, notably the attention to activity as central to individual personality [], the renewed concern with levels of integration theory [], and the burgeoning interest in Vygotsky's writings on language, thought, and culture []. There are also the continuing attempts to locate Freud's positive contributions in a historical materialist frame [].Where, then, is psychological anthropology? As always, producing a richness of suggestive materials — such as those on varying conceptions of the self — but, as a glance at the pages of Ethos will show, unfortunately not engaged in fundamental theoretical innovation. By way of illustration, let me cite Spindler's The Making of Psychological Anthropology, a collection of articles by major figures, past and present. Spindler's introductory essay is thoughtful; always the teacher, he presents with consideration and modesty the history of the field, the disfavor into which it fell (in large part due to the methodlogical travesties of national character studies), and its stubborn persistence (following from the pervasive interest in the psychological dimension that has always characterized cultural anthropology). He summarizes ongoing problems as perceived from within the field, and as the major difficulty to be overcome pinpoints cultural overdeterminism and its inadequacy for explaining variations. The solution? Not the necessity of respecting history and focussing on how individuals variously understand and relate (according to their individual histories) to the established structures whereby particular societies produce, allocate, and consume basic goods, and how they variously respond to disjunctions in these structures even as they reproduce them. Instead Spindler writes, ... if we are to escape the double bind of our cultural overdeterminism, we are going to have to go beyond culture and even ecology, to biochemistry, to physiology and neurology, to genetics — to biology in the broadest sense of the term [].In closing, let me say to the reader, do not simply turn away in dismay. One must conclude that it is imperative to continue to build a solid alternative theory of relations among individual behaviors, individual understandings, cultural values, and societal processes, or, in other words, to replace a non-historical and essentially biological paradigm with a dialectical and materialist view of human action.Eleanor Leacock is Professor of Anthropology and Chair at the City College, City University of New York.

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Regulation of protein kinase activities in PC12 pheochromocytoma cells.

Stimulation of serine protein kinase activity (referred to as S6 kinase) occurs within minutes of addition of nerve growth factor (NGF) to PC12 rat pheochromocytoma cells. This enzyme activity is not related to the cAMP-dependent protein kinase (protein kinase A) or the Ca2+- and phospholipid-dependent protein kinase (protein kinase C), two other protein kinases potentially involved in signal transduction. Two peaks of NGF-stimulated S6 phosphotransferase activity are observed upon ion exchange chromatography; one that comigrates with the serine kinase previously described in chicken embryo fibroblasts and another with distinct elution properties. Several other factors are also found to regulate S6 phosphotransferase activity in PC12 cells including epidermal growth factor, insulin, and phorbol myristate acetate. Dibutyryl cAMP stimulates S6 phosphotransferase activity; however, this activity is strongly inhibited by the protein kinase A heat stable inhibitor. At least two mechanisms exist through which the NGF-stimulated S6 kinase activity can be regulated, one that apparently can use protein kinase C whereas the other(s) does not. The potential roles of these protein kinase activities in signal transduction and regulation of cell growth and differentiation is discussed.