Evidence for a phytochrome-mediated phototropism in etiolated pea seedlings

Entirely etiolated pea seedlings (Pisum sativum, L. cv Alaska) were tested for a phototropic response to short pulses of unilateral blue light. They responded with small curvatures resembling in fluence-dependence and kinetics of development a phytochrome-mediated phototropic response previously described in maize mesocotyls. Irradiations from above with saturating red or far-red light, either immediately before or after the unilateral phototropic stimulus, strongly reduced or eliminated subsequent positive phototropic curvature. Only blue light from above, however, entirely eliminated curvature at all fluences of stimulus. It is concluded that the phototropism is primarily a result of phytochrome action.     

A novel inositol-phospholipid-specific phospholipase C. Rapid purification and characterization

A novel bovine brain inositol-phospholipid-specific phospholipase C has been identified on the basis of chromatographic behaviour and purified to apparent homogeneity by a rapid three-step procedure. The purified enzyme has a molecular mass of 85 kDa on SDS/polyacrylamide gel electrophoresis and a specific activity of 24 mumol.min-1.mg-1. The enzyme is dependent on Ca2+ and shows a marked preference for inositol phospholipid substrates. The unique nature of this polypeptide was confirmed through partial protein sequence analysis.     

A 22-amino-acid peptide restores DNA-binding activity to dimerization-defective mutants of the estrogen receptor.

We have identified residues within the estrogen receptor that are required for dimerization and high-affinity DNA binding. A 22-amino-acid peptide encompassing these residues was sufficient to restore DNA-binding activity to a mutant receptor lacking most of the hormone-binding domain. Point mutagenesis of the fusion protein confirmed that this sequence continued to mediate dimerization in a manner similar to that within the native receptor, although its position relative to the DNA-binding domain was appreciably altered.     

Phase I study of combination recombinant interleukin-2 and interferon gamma in patients with advanced malignancies

A phase I trial of interleukin-2 and interferon gamma combination treatment in patients with advanced malignancies was performed based on preclinical in vitro and in vivo data which demonstrated synergistic antitumor effect. The toxicities, immune parameters, and tumor responses are described. The clinical and biologic maximal tolerated doses were extrapolated from these data.     

Expression of ACh-activated channels and sodium channels by messenger RNAs from innervated and denervated muscle

Xenopus oocytes were used to express polyadenylated messenger RNAs (mRNAs) encoding acetylcholine receptors and voltage-activated sodium channels from innervated and denervated skeletal muscles of cat and rat. Oocytes injected with mRNA from denervated muscle acquired high sensitivity to acetylcholine, whereas those injected with mRNA from innervated muscle showed virtually no response. Hence the amount of translationally active mRNA encoding acetylcholine receptors appears to be very low in normally innervated muscle, but increases greatly after denervation. Conversely, voltage-activated sodium currents induced by mRNA from innervated muscle were about three times larger than those from denervated muscle; this result suggests that innervated muscle contains more mRNA coding for sodium channels. The sodium current induced by mRNA from denervated muscle was relatively more resistant to block by tetrodotoxin. Thus a proportion of the sodium channels in denervated muscle may be encoded by mRNAs different from those encoding the normal channels.     

Lack of differentiation following mouse serum treatment of cultured chick limb myoblasts

This investigation was conducted to assess the effects of mouse serum on chick skeletal muscle cell differentiation. In light of earlier findings of altered membrane phospholipid metabolism following mouse serum treatment of Friend erythroleukemic and chick chondrogenic cells, it was of interest to determine whether similar changes would modulate the fusion of mononucleated myoblasts, which is necessary for the formation of multinucleated skeletal muscle fibers. When mouse serum is added to low density cultures of enriched chick myoblasts shortly following cell attachment to the substratum, fusion is inhibited and neutral lipid accumulation ensues. There is an early inhibitory effect on DNA synthesis but not on protein synthesis. There is no increase in the uptake of 2-deoxyglucose following insulin stimulation of the cells, which suggests that while the cells are accumulating large amounts of lipid, they are not being converted into typical adipocytes. Finally, even in cultures of mouse serum-treated cells that undergo significant fusion, one observes thinner myotubes that do not spontaneously contract as do those of control cultures, as well as a disorganization of fluorescently stained actin and myosin myofilaments. These findings demonstrate that mouse serum acts in a dose-dependent manner, is not cytotoxic to the cells, but is capable of modulating normal developmental events of myoblasts as reported for other cell and tissue types.     

Taking care of patients--does it matter whether the physician is a woman?

Researchers have recently begun to compare male and female physicians'' attitudes toward patients, medical knowledge, and practice styles. Although women start medical school with more "humanistic views," the conservative effect of medical socialization on both male and female students attenuates these differences. While some studies suggested that men are more scientifically knowledgeable, recent studies showed no significant differences in physicians'' medical knowledge. Male and female physicians also had comparable diagnostic and therapeutic behavior. In the intimate world of physicians and patients, however, there were notable differences. Women physicians seemed better able to communicate sensitivity and caring to patients, which may account for the common perception that women are more caring and empathic physicians. Medical educators may wish to study more closely female physicians'' communication styles to identify these behaviors and inculcate them into all physicians.