The response of serum ceruloplasmin to injections of walker 256 tumor cells or turpentine into rats

The subcutaneous injection of Walker 256 carcinosarcoma cells into a rat was followed by a pronounced increase in plasma ceruloplasmin activity. This lasted only about 3 weeks even though the tumors were still enlarging rapidly. Based upon studies with⁶⁷Cu, the increase in plasma ceruloplasmin seemed to reflect increased production of the enzyme by the livers of rats bearing the tumors. Injections of turpentine also raised plasma ceruloplasmin, but to a significantly lesser extent and normal values were reached within 2 weeks.     

Denture Wearers' Awareness of their Vertical Dimension

A method of analyzing facial proportions in evaluating occlusal vertical dimension was used in a test on 71 complete denture wearers aiming to find a way to rank denture wearers with different stages of reduced vertical dimension and development an instruction for patients' self judgment. By use of face drawings on a proforma the patients ranked themselves into one of four classes. The investigator also ranked the patients into these classes. There was a significant correlation (p<0.01) between the ranking by patient and investigator. The face proportions were also measured with an instrument. The distances nasion-rima oris and subnasale-gnathion were established. When ranking into classes, there was a significant (p<0.0001) correlation between the ranking by the investigator and the measurements. The results show that it may be possible to use information of facial proportions to give complete denture wearers a way of assessment of face height and thus a reason to consult a dentist in case of suspicion of reduced vertical dimension.     

Photoproduction of h(2) from cellulose by an anaerobic bacterial coculture

Cellulomonas sp. strain ATCC 21399 is a facultatively anaerobic, cellulose-degrading microorganism that does not evolve hydrogen but produces organic acids during cellulose fermentation. Rhodopseudomonas capsulata cannot utilize cellulose, but grows photoheterotrophically under anaerobic conditions on organic acids or sugars. This report describes an anaerobic coculture of the Cellulomonas strain with wild-type R. capsulata or a mutant strain lacking uptake hydrogenase, which photoevolves molecular hydrogen by the nitrogenase system of R. capsulata with cellulose as the sole carbon source. In coculture, the hydrogenase-negative mutant produced 4.6 to 6.2 mol of H(2) per mol of glucose equivalent, compared with 1.2 to 4.3 mol for the wild type.     

A dodecamer of globin chains is the principal functional subunit of the extracellular hemoglobin of Lumbricus terrestris

Repeated dissociation of the approximately 3600-kDa hexagonal bilayer extracellular hemoglobin of Lumbricus terrestris in 4 M urea followed by gel filtration at neutral pH produces a subunit that retains the oxygen affinity of the native molecule (approximately 12 torr), but only two-thirds of the cooperativity (nmax = 2.1 +/- 0.2 versus 3.3 +/- 0.3). The mass of this subunit was estimated to be 202 +/- 15 kDa by gel filtration and 202 +/- 26 kDa from mass measurements of unstained freeze-dried specimens by scanning transmission electron microscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of this subunit showed that it consists predominantly of the heme-containing subunits M (chain I, 17 kDa) and T (disulfide-bonded chains II-IV, 50 kDa). Mixing of subunits M and T isolated concurrently with the 200-kDa subunit resulted in partial association into particles that had a mass of 191 +/- 13 kDa determined by gel filtration and 200 +/- 38 kDa determined by scanning transmission electron microscopy and whose oxygen affinity and cooperativity were the same as those of the 200-kDa subunit. The results imply that the 200-kDa subunit is a dodecamer of globin chains, consisting of three copies each of subunits M and T (3 x chains (I + II + III + IV], in good agreement with the mass of 209 kDa calculated from the amino acid sequences of the four chains, and represents the largest functional subunit of Lumbricus hemoglobin. Twelve copies of this subunit would account for two-thirds of the total mass of the molecule, as suggested earlier (Vinogradov, S. N., Lugo, S. L., Mainwaring, M. G., Kapp, O. H., and Crewe, A. V. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 8034-8038). The retention of only partial cooperativity by the 200-kDa subunit implies that full cooperativity is dependent on the presence of a complete hexagonal bilayer structure, wherein 12 200-kDa subunits are linked together by approximately 30-kDa heme-deficient chains.     

Early recognition in the Rhizobium meliloti-alfalfa symbiosis: root exudate factor stimulates root adsorption of homologous rhizobia.

Adsorption of Rhizobium meliloti to alfalfa roots before their infection and nodule formation shows the specificity of the symbiotic association (G. Caetano-Anollés and G. Favelukes, Appl. Environ. Microbiol. 52:377-382, 1986). The time course of specific adsorption of R. meliloti (10(3) to 10(4) cells per ml) to roots shows an initial lag period of 3 h, suggesting that either or both symbionts must become conditioned for the adsorption process. Preincubation of R. meliloti L5-30 for 3 h with dialyzed alfalfa root exudate (RE) markedly increased early adsorption of rhizobia to alfalfa roots. The activity in RE was linked to a nondialyzable, thermolabile, trypsin-sensitive factor(s), very different from the root-exuded flavonoid compounds also involved in early Rhizobium-legume interactions. The lack of activity in the RE from plants grown in 5 mM NO3- suggested its negative regulation by the nitrogen nutritional status of the plant. Preincubation of R. meliloti with heterologous clover RE did not stimulate adsorption of rhizobial cells to roots. A short pretreatment of RE with homologous (but not heterologous) strains eliminated the stimulatory activity from solution. The stimulation of adsorption of R. meliloti to alfalfa roots was strongly dependent on the growth phase of the rhizobia, being greater at the late exponential stage. Nevertheless, the capacity of R. meliloti L5-30 to eliminate from solution the stimulatory activity in RE appeared to be constitutive in the rhizobia. The low concentration of rhizobial cells used in these experiments was critical to detect the stimulation of adsorption. The early interaction of spontaneously released alfalfa root macromolecular factor(s) and free-living R. meliloti, which shows the specificity and regulatory properties characteristic of infection and nodulation, would be an initial recognition event in the rhizosphere which triggers the process of symbiotic association.     

Protein kinase C gamma expression mimics phorbol ester-induced transcriptional activation of a murine VL30 enhancer element

Protein kinase C (PKC), a critical component in the regulation of cell growth, is thought to participate in transmitting the signals of certain cell surface receptor activation events to the nucleus. We have previously shown that stable expression of the PKC gamma isoenzyme in NIH 3T3 cells causes altered growth and enhanced tumorigenicity. In this report, we show that transient expression of the PKC gamma isoenzyme can trans-activate a murine VL30 enhancer element in a pattern similar to that of the phorbol ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate. In contrast, ras activation of this element is distinct both quantitatively and qualitatively from PKC gamma and 12-O-tetradecanoylphorbol-13-acetate activation. These results provide direct evidence that PKC is the cellular mediator in the activation of phorbol ester-responsive genes and suggest a mechanism by which abnormal PKC expression might lead to altered growth control by changing the pattern of cellular gene expression.     

Transforming growth factor-beta inhibits the production of IgG, IgM, and IgA in human lymphocyte cultures.

Transforming growth factor beta (TGF beta) has potent immunoregulatory effects acting on both T and B cells. It strongly inhibits secretion of IgG and IgM in human and murine B cell cultures, but has been shown to have an enhancing effect on IgA production in the mouse. We have studied the effect of TGF beta on the production of IgA in human lymphocyte cultures. The addition of TGF beta to pokeweed-stimulated peripheral blood lymphocytes resulted in a suppression of IgA production of both subclasses, similar in magnitude to the suppression of IgG and IgM production. Membrane IgA expression was not increased by culturing tonsillar lymphocytes with TGF beta. In conclusion, we find no evidence for a selective enhancing effect of TGF beta on IgA synthesis in humans, in contrast to the findings reported in mice.     

Preferential use of a T cell receptor V beta gene by acetylcholine receptor reactive T cells from myasthenia gravis-susceptible mice.

Experimental autoimmune myasthenia gravis (EAMG) is an important model for testing current concepts in autoimmunity and novel immunotherapies for autoimmune diseases. The EAMG autoantigen, acethylcholine receptor (AChR), is structurally and immunologically complex, a potential obstacle to the application of therapeutic strategies aimed at oligoclonal T cell populations. Inasmuch as we had previously shown that the clonal heterogeneity of T cell epitope recognition in EAMG was unexpectedly limited, we examined TCR V beta expression. AChR primed lymph node T cells and established AChR reactive T cell clones from EAMG-susceptible C57BL/6 (B6; H-2b, Mls-1b) mice showed preferential utilization of the TCR V beta 6 segment of the TCR. After in vivo priming and in vitro restimulation for 7 days with AChR or a synthetic peptide bearing an immunodominant epitope, V beta 6 expressing lymph node cells (LNC) were expanded several-fold, accounting for up to 75% of recovered viable CD4+ cells. The LNC of B6.C-H-2bm12 (bm12; H-2bm12, Mls-1b) mice, which proliferated in response to AChR but not to the B6 immunodominant peptide, failed to expand V beta 6+ cells. Inasmuch as nonimmune bm12 and B6 animals had similar numbers of V beta 6+ LNC (4-5%), this suggested that structural requirements for TCR recognition of Ag/MHC complexes dictated V beta usage. Results concerning peptide reactivity and V beta 6 expression among T cells from (B6 x bm12)F1 animals also suggested that structure-function relationships, rather than negative selection or tolerance, accounted for the strain differences between B6 and bm12. To examine the potential effects of thymic negative selection of V beta 6+ cells on the T cell response to AChR, CB6F1 (H-2bxd, Mls-1b; V beta 6-expressing) and B6D2F1 (H-2bxd, Mls-1axb; V beta 6-deleting) strains were analyzed for AChR and peptide reactivity and V beta 6 expression. Both F1 strains responded well to AChR but the response of B6D2F1 mice to peptide was significantly reduced compared to CB6F1. Short and long term cultures of peptide-reactive B6D2F1 LNC showed no expansion of residual V beta 6+ cells, although similar cultures of CB6F1 LNC were composed of more than 60% V beta 6+ cells. The results from the F1 strains further indicated that the T cell repertoire for peptide was highly constrained and that non-V beta 6 expressing cells could only partially overcome Mls-mediated negative selection of V beta 6+ TCR capable of recognizing peptide.(ABSTRACT TRUNCATED AT 400 WORDS)     

Information contents and dinucleotide compositions of plant intron sequences vary with evolutionary origin

The DNA sequence composition of 526 dicot and 345 monocot intron sequences have been characterized using computational methods. Splice site information content and bulk intron and exon dinucleotide composition were determined. Positions 4 and 5 of 5 splice sites contain different statistically significant levels of information in the two groups. Basal levels of information in introns are higher in dicots than in monocots. Two dinucleotide groups, WW (AA, AU, UA, UU) and SS (CC, CG, GC, GG) have significantly different frequencies in exons and introns of the two plant groups. These results suggest that the mechanisms of splice-site recognition and binding may differ between dicot and monocot plants.