Activated lymphocytes trigger lymphoblast extravasation.

Intraperitoneal stimulation of adoptively sensitized rats with bacterial antigen promotes the localization of lymphoblasts at the site of antigen deposition. Lymphoblast extravasation activity (LEA) is generated only when specifically immune donor lymphocytes and the recipients of these cells share at least on Ag-B haplotype. However, if the specificity criteria for its formation are satisfied, LEA promotes the local development of lymphoblasts of all available specificities and irrespective of their Ag-B genotype. Allogeneic lymphoblasts do not participate actively in the delayed inflammatory reaction even when they are passively recruited into exudates. The results suggest that LEA is a T cell-derived mediator that amplifies the delayed type hypersensitivity reaction by directing recently activated lymphocytes into lesions.     

Functional changes in the structure of the SRP GTPase on binding GDP and Mg2+GDP.

Ffh is a component of a bacterial ribonucleoprotein complex homologous to the signal recognition particle (SRP) of eukaryotes. It comprises three domains that mediate both binding to the hydrophobic signal sequence of the nascent polypeptide and the GTP-dependent interaction of Ffh with a structurally homologous GTPase of the SRP receptor. The X-ray structures of the two-domain 'NG' GTPase of Ffh in complex with Mg2+GDP and GDP have been determined at 2.0 A resolution. The structures explain the low nucleotide affinity of Ffh and locate two regions of structural mobility at opposite sides of the nucleotide-binding site. One of these regions includes highly conserved sequence motifs that presumably contribute to the structural trigger signaling the GTP-bound state. The other includes the highly conserved interface between the N and G domains, and supports the hypothesis that the N domain regulates or signals the nucleotide occupancy of the G domain.     

Computerized topographical analysis of functionally homogeneous neuronal sets.

A computer-assisted analysis of the spatial distribution of neurons having homogeneous characteristics is described in this paper. The camera lucida drawings of sections of a brain nucleus and the points representing the neurons labeled on the basis of a specific behavior of discharge rates were digitized on a personal computer Amiga 2000 or IBM compatible. Our software provided: a) the computerized, stereotaxically oriented reconstruction of the stored sections and of the plotted neurons; b) the identification within each section of the mass center (MC) of the units sharing a given behavior and of the area where the density of such neurons was maximal (MDA). The routine was tested on the spatial distribution of neuronal responses to serotonin in the lateral vestibular nucleus.     

Controlling intraoperative and postoperative nasal bleeding.

An indwelling nasal suction tampon is described that effectively controls both intraoperative and postoperative nasal hemorrhage. The significant benefits of this device are better intraoperative control for the surgeon and less complicated postoperative recovery. I do not have any financial involvement in this device, but I would like other nasal surgeons to benefit from its particular advantages. The device is available under the trade name Instant and may be obtained from Innovations by Westmed, 3351 E. Hemisphere Loop, Tucson, Ariz. 85706; (602) 294-7987.     

Carotenoid synthesis in Streptomyces setonii ISP5395 is induced by the gene crtS, whose product is similar to a sigma factor

In many species of actinomycetes, carotenogenesis can be photoinduced. The capacity to respond to photoinduction is, however unstable and, in various strains of Streptomyces, is lost at a relatively high frequency. In Streptomyces setonii ISP5395, which normally produces no carotenoids, carotenoid-producing mutants can be obtained following protoplast regeneration. We report here the characterization of a gene, crtS, which was isolated from one such mutant and can confer on wild-type S. setonii ISP5395 cells the capacity to synthesize carotenoids. Sequence analysis of crtS reveals an open reading frame, which shows homology to genes that encode alternative sigma factors in Bacillus subtilis. We propose that crtS encodes a sigma factor which is necessary for the expression of a cryptic gene(s) for carotenoid biosynthesis in S. setonii ISP5395.     

Assay of 1L-myo-inositol-1-phosphatase using a fluorometric method.

1L-myo-Inositol-1-phosphatase, an enzyme purified from brain tissues, catalyzes the dephosphorylation of 1L-myo-inositol 1-phosphate. This enzyme has become the subject of intense research interest, since myo-inositol is needed for the resynthesis of phosphatidylinositol. We have developed a sensitive fluorometric assay for detecting the activity of 1L-myo-inositol-1-phosphatase. The assay is based on o-aminobenzoyl beta-glycerophosphate fluorescence, according to the following principles: (I) The fluorescence yield of o-aminobenzoyl beta-glycerophosphate is increased by 2.75-fold in the presence of saturating concentrations of bovine serum albumin. (II) o-Aminobenzoyl beta-glycerophosphate has the same fluorescence yield as o-aminobenzoyl glycerol, but the latter does not bind to bovine serum albumin. (III) Dephosphorylation of the substrate, catalyzed by the monophosphatase, makes less o-aminobenzoyl beta-glycerophosphate available for binding to bovine serum albumin, thereby producing a decrease in the fluorescence intensity.