Androgenic stimulation of endocytosis, amino acid and hexose transport in mouse kidney cortex involves increased calcium fluxes

Testosterone was previously shown to induce an early (less than 1 min) receptor-dependent stimulation of endocytosis, hexose and amino acid transport in mouse kidney cortex (Koenig, H., Goldstone, A. and Lu, C.Y. (1982) Biochem. Biophys. Res. Commun. 104, 165-172). Testosterone (10(-8) M) has now been found to stimulate rapidly (less than 30 s) the influx and efflux of 45Ca2+ in cortex slices. Testosterone also decreased mitochondrial 45Ca and augmented soluble 45Ca, indicating a mobilization of intracellular calcium. Incubation of cortex slices in calcium-free medium without or with 2.5 mM EGTA decreased basal endocytosis, hexose and amino acid transport and blocked the hormonal response. 100 microM verapamil blocked the hormonal response without affecting basal transport. The calcium ionophore A23187 rapidly stimulated endocytosis, hexose and amino acid transport. These data indicate that androgenic stimulation of membrane transport functions involves an increased influx of extracellular calcium and a mobilization of intracellular calcium. Increased cytosolic Ca2+ is probably the regulatory signal for these transport processes.     

Interpretation of hypochromic and hyperchromic intensity changes in the Raman spectra of polypeptides and polynucleotides undergoing transition.

The hyperchromic and hypochromic changes in the intensity of the amide-I and amide-III lines of polypeptides and certain ring vibrations of the bases of polynucleotides are shown to be related to similar changes in the lower energy uv absorption bands. The selection rules strictly limit the pairs of excited electronic states that can contribute to the elements of the polarizability matrix. An energy-dependent term in this equation weights the contribution of the pairs of electronic transitions in favor of those involving the lower energy transitions. For both polypeptides and polynucleotides, there is a large hypochromic inensity change in the first π → π* exciton band upon the coil-to-helix transition. Through the selection rules, certain conformationally sensitive Raman lines are shown to derive their intensity predominantly from this band and hence also display hypochromism. Again, through an application of the selection rules, certain Raman lines can be demonstrated to depend predominantly for their intensity upon the n → π* transition, and consequently have the opposite hyperchromic intensity change upon the same conformational transition.     

Partial monosomy 10p syndrome

A newborn infant with monosomy 10p13 is reported. The clinical signs and symptoms of the present case are compared with those of previously described cases. Although there is no pathognomonic feature, a characteristic monosomy 10p syndrome is recognizable.     

Action of veratridine on acetylcholinesterase in cultures of rat muscle cells

Studies on cultures of embryonic rat muscle cells have suggested that the presence of collagen-tailed forms may be correlated with spontaneous contractile activity: these forms disappear in the presence of tetrodotoxin which blocks the sodium channels involved in the propagation of action potentials. The effect of veratridine, a drug which maintains the sodium channels in the open state, was studied. It is shown here that in young cultures veratridine provoked a dramatic increase in total acetylcholinesterase activity and changed the distribution of the molecular forms of the enzyme, increasing the proportion and absolute amount of the A12 form. In order to elucidate the mechanism of action of this drug, the effects of various ions, ionophores, or other agents that modify the ionic permeabilities of membranes were also investigated.     

The preparation of a sarcolemmal fraction from evacuated muscle slices

A novel procedure is described for preparing a plasma membrane fraction from skeletal muscle (i.e., sarcolemma). The procedure entails evacuating the myoplasm from muscle slices as a preliminary step to homogenization and fractionation. The evacuated muscle slices are composed of a stroma-containing sarcolemma, which is then homogenized and fractionated, utilizing a sequence of differential and discontinuous sucrose density gradient centrifugations. On the basis of electron microscopy, selective enzyme markers and α-bungarotoxin binding in innervated and denervated muscles, the fraction most enriched with sarcolemma is recovered from the 0.5/0.7 M interface of a discontinuous sucrose gradient.     

Macrophage factor controlling differentiation of B cells.

Peritoneal macrophages of the mouse produce, in response to cell wall components of Gram-negative bacteria (lipopolysaccharide and lipoproteins), a factor that causes antigen-stimulated B cells of differentiate into antibody-producing cells. Unlike lipopolysaccharide, this factor is not mitogenic for B cells. Production of the macrophage factor does not depend on participation of T cells or other accessory cells since it is readily produced by several cloned macrophage cell lines as well as by peritoneal macrophages of athymic nude mice. The factor is active only in conjunction with antigen. T cells, although apparently not necessary, amplify its effect. The factor induces phenotypic differentiation of B cell precursors as selectively as thymopoietin induces differentiation of prothymocytes.     

Natural Occurrence of Helenium Virus S in Impatiens holstii

Samples of commercially grown Impatiens holstii from several sources in Minnesota contained a carlavirus which serologically was closely related, if not identical with Helenium virus S described earlier in Germany. The two viruses have similar experimental host ranges and caused similar cytopathogenic effects. After mechanical transmission the Impatiens isolate produced less severe symptoms in Impatiens than the Helenium isolate. Only the latter isolate was transmitted by Myzus persicae in the non-persistent manner.