Changes in magnetic resonance images in human skeletal muscle after eccentric exercise

To investigate the time-course of changes in transverse relaxation time (T₂) and cross-sectional area (CSA) of the quadriceps muscle after a single session of eccentric exercise, magnetic resonance imaging was performed on six healthy male volunteers before and at 0, 7, 15, 20, 30 and 60 min and 12, 24, 36, 48, 72 and 168 h after exercise. Although there was almost no muscle soreness immediately after exercise, it started to increase 1 day after, peaking 1–2 days after the exercise (P<0.01). Immediately after exercise, T₂ increased significantly in the rectus femoris, vastus lateralis and intermedius muscles (P<0.05) and decreased quickly continuing until 60 min after exercise. At and after the 12th h, a significant increase was perceived again in the T₂ values of the vastus lateralis and intermedius muscles (P<0.01) [maximum 9.3 (SEM 2.8)% and 10.9 (SEM 2.2)%, respectively]. The maximal values were exhibited at 24–36 h after exercise. In contrast, the rectus femoris muscle showed no delayed-stage increase. Also, in CSA, an increase after 12 h was observed in addition to the one immediately after exercise in the vastus lateralis, intermedius and medialis and quadriceps muscles as a whole (P < 0.01), reaching the maximal values at 12–24 h after exercise. The plasma creative kinase activity remained unchanged up to 24 h after and then increased significantly 48 h after exercise (P < 0.05). Beginning 12 h after exercise, the subjects whose T₂ and CSA increased less than the others displayed a faster decrease in muscle soreness. These results suggested that T₂ and CSA displayed bimodal responses after eccentric exercise and the time-courses of changes in them were similar to those in muscle soreness.     

Various competitive interactions explain niche separation in crop‐dwelling web spiders

Competition for resources is a major organizing principle in communities of organisms that share similar ecological niches. Niche separation by means of exploitation or interference competition was investigated in two taxa of crop‐inhabiting spiders that overlap in microhabitat use and have similar web design. Competition for prey and web sites was tested in microcosm experiments with the most common species that build sheet‐webs: Enoplognatha gemina (Theridiidae) and Alioranus pastoralis (Linyphiidae). A field survey over the crop season provided data on spatial and temporal dispersion of Enoplognatha spp. (Theridiidae) and linyphiid spiders (Linyphiidae) and on availability of prey over the season. In the microcosm experiments, both taxa took springtails as prey, but only Enoplognatha fed on aphids. Differences in diet, however, could not be attributed to either exploitative or interference competition. Spatial separation of websites was attained by vertical displacement of webs in the vegetation (Enoplognatha) and by avoidance of patches occupied by conspecific or heterospecific individuals (linyphiids). In the field, densities of linyphiids and Enoplognatha were correlated negatively and webs were over‐dispersed relative to a random distribution. Both taxa colonized the field at the start of the season; linyphiids colonized as adults, quickly reproduced, and had a second adult peak; Enoplognatha matured in the middle of the season and their numbers remained fairly constant over the season. The combined experimental manipulations and field data suggest that niche separation occurs at different scales. The hypothesis of competition for websites was partially supported, while prey preference (or tolerance) and temporal differences in life history stages also may explain the negative correlations between densities of the two taxa.     

Regulation of Ferricyanide Reduction by Epidermal Tissue

Ferricyanide reduction by epidermal strips of Commelina communisis stimulated by plasmolysis, and this stimulation is partiallyreversed by re-hydration. The reduction of ferricyanide takesplace only in the guard cells. KCN stimulates ferricyanide reduction, indicating that NADHserves as an electron donor. Catalase, which inhibits NAD(P)Hdriven oxygen uptake [Askerlund et al. (1987) Physiol. Plant.71: 9–19., Pantoja and Willmer (1988) Planta 174: 44–50.]enhances ferricyanide reduction and this stimulation is evidentmainly in the non-plasmolysed tissues. Differences between thenon-pretreated tissues and the plasmolysed ones are discussed. (Received July 11, 1989; Accepted November 2, 1989)     

Streptococcus pneumoniae Cell-Wall-Localized Phosphoenolpyruvate Protein Phosphotransferase Can Function as an Adhesin: Identification of Its Host Target Molecules and Evaluation of Its Potential as a Vaccine

In Streptococcus pneumonia, phosphoenolpyruvate protein phosphotransferase (PtsA) is an intracellular protein of the monosaccharide phosphotransferase systems. Biochemical and immunostaining methods were applied to show that PtsA also localizes to the bacterial cell-wall. Thus, it was suspected that PtsA has functions other than its main cytoplasmic enzymatic role. Indeed, recombinant PtsA and anti-rPtsA antiserum were shown to inhibit adhesion of S. pneumoniae to cultured human lung adenocarcinoma A549 cells. Screening of a combinatorial peptide library expressed in a filamentous phage with rPtsA identified epitopes that were capable of inhibiting S. pneumoniae adhesion to A549 cells. The insert peptides in the phages were sequenced, and homologous sequences were found in human BMPER, multimerin1, protocadherin19, integrinβ4, epsin1 and collagen type VIIα1 proteins, all of which can be found in A549 cells except the latter. Six peptides, synthesized according to the homologous sequences in the human proteins, specifically bound rPtsA in the micromolar range and significantly inhibited pneumococcal adhesion in vitro to lung- and tracheal-derived cell lines. In addition, the tested peptides inhibited lung colonization after intranasal inoculation of mice with S. pneumoniae. Immunization with rPtsA protected the mice against a sublethal intranasal and a lethal intravenous pneumococcal challenge. In addition, mouse anti rPtsA antiserum reduced bacterial virulence in the intravenous inoculation mouse model. These findings showed that the surface-localized PtsA functions as an adhesin, PtsA binding peptides derived from its putative target molecules can be considered for future development of therapeutics, and rPtsA should be regarded as a candidate for vaccine development.     

Toxin-Independent Virulence of Bacillus anthracis in Rabbits

The accepted paradigm states that anthrax is both an invasive and toxinogenic disease and that the toxins play a major role in pathogenicity. In the guinea pig (GP) model we have previously shown that deletion of all three toxin components results in a relatively moderate attenuation in virulence, indicating that B. anthracis possesses an additional toxin-independent virulence mechanism. To characterize this toxin-independent mechanism in anthrax disease, we developed a new rabbit model by intravenous injection (IV) of B. anthracis encapsulated vegetative cells, artificially creating bacteremia. Using this model we were able to demonstrate that also in rabbits, B. anthracis mutants lacking the toxins are capable of killing the host within 24 hours. This virulent trait depends on the activity of AtxA in the presence of pXO2, as, in the absence of the toxin genes, deletion of either component abolishes virulence. Furthermore, this IV virulence depends mainly on AtxA rather than the whole pXO1. A similar pattern was shown in the GP model using subcutaneous (SC) administration of spores of the mutant strains, demonstrating the generality of the phenomenon. The virulent strains showed higher bacteremia levels and more efficient tissue dissemination; however our interpretation is that tissue dissemination per se is not the main determinant of virulence whose exact nature requires further elucidation.     

Human gut mycobiota tune immunity via CARD9-dependent induction of anti-fungal IgG antibodies

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Genetic population structure of Hemigrammocypris rasborella (Cyprinidae) inferred from mtDNA sequences

The genetic population structure of the small cyprinid Hemigrammocypris rasborella, distributed widely in lowlands of western Japan, was examined using partial sequence data of mitochondrial DNA (mtDNA). Molecular phylogenetic analysis revealed that the populations of the western Kyushu region were markedly differentiated from all eastern populations, such that the groups would be comparable to different species; their divergence was inferred to have occurred in the Late Miocene–Pliocene. Also, a largely divergent mtDNA group (with divergence in the early Pleistocene) was found in the Sanyo and northeastern Shikoku regions, forming a secondary contact zone in the western Kinki with the eastern mtDNA group. To date, these aspects of the population structure of H. rasborella appear to be unique among lowland fishes in western Japan. Deeper understanding of the formation processes of freshwater faunas in western Japan will require further comparisons of the phylogeographic patterns and ecological traits of constituent species.     

Systemic antitumor protection by vascular-targeted photodynamic therapy involves cellular and humoral immunity

Vascular-targeted photodynamic therapy (VTP) takes advantage of intravascular excitation of a photosensitizer (PS) to produce cytotoxic reactive oxygen species (ROS). These ROS are potent mediators of vascular damage inducing rapid local thrombus formation, vascular occlusion, and tissue hypoxia. This light-controlled process is used for the eradication of solid tumors with Pd-bacteriochlorophyll derivatives (Bchl) as PS. Unlike classical photodynamic therapy (PDT), cancer cells are not the primary target for VTP but instead are destroyed by treatment-induced oxygen deprivation. VTP initiates acute local inflammation inside the illuminated area accompanied by massive tumor tissue death. Consequently, in the present study, we addressed the possibility of immune response induction by the treatment that may be considered as an integral part of the mechanism of VTP-mediated tumor eradication. The effect of VTP on the host immune system was investigated using WST11, which is now in phase II clinical trials for age-related macular degeneration and intended to be evaluated for cancer therapy. We found that a functional immune system is essential for successful VTP. Long-lasting systemic antitumor immunity was induced by VTP involving both cellular and humoral components. The antitumor effect was cross-protective against mismatched tumors, suggesting VTP-mediated production of overlapping tumor antigens, possibly from endothelial origin. Based on our findings we suggest that local VTP might be utilized in combination with other anticancer therapies (e.g., immunotherapy) for the enhancement of host antitumor immunity in the treatment of both local and disseminated disease. Y.S. and A.S are the incumbents of the Tillie and Charles Lubin Professorial Chair in Biochemical Endocrinology, and the Robert and Yaddele Sklare Professorial Chair in Biochemistry, respectively. S.J. is the incumbent of the Pauline Recanati Career Development Chair. D.P. in partial fulfillment of her PhD Thesis requirements at the Feinberg graduate school of the Weizmann Institute of Science.