Cellular Changes during Renal Failure-Induced Inflammatory Aortic Valve Disease

Background

Aortic valve calcification (AVC) secondary to renal failure (RF) is an inflammation-regulated process, but its pathogenesis remains unknown. We sought to assess the cellular processes that are involved in the early phases of aortic valve disease using a unique animal model of RF-associated AVC.

Methods

Aortic valves were obtained from rats that were fed a uremia-inducing diet exclusively for 2, 3, 4, 5, and 6 weeks as well as from controls. Pathological examination of the valves included histological characterization, von Kossa staining, and antigen expression analyses.

Results

After 2 weeks, we noted a significant increase in urea and creatinine levels, reflecting RF. RF parameters exacerbated until the Week 5 and plateaued. Whereas no histological changes or calcification was observed in the valves of any study group, macrophage accumulation became apparent as early as 2 weeks after the diet was started and rose after 3 weeks. By western blot, osteoblast markers were expressed after 2 weeks on the diet and decreased after 6 weeks. Collagen 3 was up-regulated after 3 weeks, plateauing at 4 weeks, whereas collagen 1 levels peaked at 2 and 4 weeks. Fibronectin levels increased gradually until Week 5 and decreased at 6 weeks. We observed early activation of the ERK pathway, whereas other pathways remained unchanged.

Conclusions

We concluded that RF induces dramatic changes at the cellular level, including macrophage accumulation, activation of cell signaling pathway and extracellular matrix modification. These changes precede valve calcification and may increase propensity for calcification, and have to be investigated further.     

Germination studies ofMolucella laevis

Seed of Molucella laevis (L.) was gathered in the years 1963-66 and germinated soon after harvest and at various intervals subsequently. All seeds showed dormancy on gathering. There was a noticeable fluctuation in the percentage of seeds germinating during storage. Dormancy persisted throughout the years of the experiment. It appears that a number of factors are operative in the inhibition of germination of M. laevis seeds. One factor is an inhibitor which may be adsorbed by active charcoal or heavy loam, involving some process which requires fluctuating temperature. Rupture of the seed-coat also improved the germination of dormant seed, and a subsequent water rinse for 24 hrs. further increased the percent of germinating seed. Immersion of the seed for 48 hrs. in gibberellic acid (G.A.), 400 ppm, greatly improved germination, but it did not completely overcome dormancy. The maximum effect (93% germinating seed) was obtained when seed pre-treated with G.A. was germinated on top of active charcoal. The optimal germination temperature was found to be a daily alternating one of 16 hrs. at 15°C and 8 hrs. at 30°C with light supplied at the latter temperature. Treated seed was sown in the screen house and found to develop normal plants and seed. The dormancy-breaking effect of G.A. lasts for at least 180 days. The fluctuations in germination of seed pre-treated with gibberellin were similar to those of the untreated ones. The effect of dormancy-breaking factors differed with year of gathering and date of application. Thus, M. laevis seeds display much heterogeneity in their germination potential.     

The cytokine midkine and its receptor RPTPζ regulate B cell survival in a pathway induced by CD74

Lasting B cell persistence depends on survival signals that are transduced by cell surface receptors. In this study, we describe a novel biological mechanism essential for survival and homeostasis of normal peripheral mature B cells and chronic lymphocytic leukemia cells, regulated by the heparin-binding cytokine, midkine (MK), and its proteoglycan receptor, the receptor-type tyrosine phosphatase ζ (RPTPζ). We demonstrate that MK initiates a signaling cascade leading to B cell survival by binding to RPTPζ. In mice lacking PTPRZ, the proportion and number of the mature B cell population are reduced. Our results emphasize a unique and critical function for MK signaling in the previously described MIF/CD74-induced survival pathway. Stimulation of CD74 with MIF leads to c-Met activation, resulting in elevation of MK expression in both normal mouse splenic B and chronic lymphocytic leukemia cells. Our results indicate that MK and RPTPζ are important regulators of the B cell repertoire. These findings could pave the way toward understanding the mechanisms shaping B cell survival and suggest novel therapeutic strategies based on the blockade of the MK/RPTPζ-dependent survival pathway.     

The unique interaction between the summer annual desert plant Salsola inermis Forssk and weevils residing on its roots: mutualism or parasitism?

1. Herbivores and parasites are likely to impose less damage on their host when their growth rate is slow and their dependency on the host is high. Accordingly, it was hypothesised that evolution would favour neutral or even beneficial interactions between a below-ground herbivore and a plant during the harsh season in a desert ecosystem. 2. This study characterised the relationship between the summer annual plant Salsola inermis Forssk (Chenopodiaceae) and weevils developing in a mud chamber attached to its roots in the Negev Desert of Israel. Plant seedlings were exposed to adult weevils (Conorhynchus palumbus Olivier or Menecleonus virgatus Schoenherr; Coleoptera: Curculionidae) in a controlled outside setting, to induce oviposition and larval establishment. The following were quantified: plant growth, above-ground biomass, fruit biomass, and fruit size, as well as relative C and N contents, and isotopic signatures (δ¹³C and δ¹⁵N) in plant tissues. 3. Exposure to weevils did not reduce plant survival but significantly and negatively affected plant growth and seed production. However, these effects were mainly due to above-ground herbivory by adults rather than root herbivory by larvae, and might have been overestimated. Interestingly, %N and δ¹⁵N were significantly higher, and the C:N ratio was significantly lower, in plants with larval establishment, suggesting that weevils affect the plant nitrogen budget. 4. The overall results do not support the notion of mutualistic interactions; yet, slow consumption, a low infestation level, and, possibly, N supplementation to the plant may enable the plant to tolerate herbivory under natural conditions.     

Macrophage migration inhibitory factor induces B cell survival by activation of a CD74-CD44 receptor complex

Macrophage migration inhibitory factor (MIF) is an upstream activator of innate immunity that regulates subsequent adaptive responses. It was previously shown that in macrophages, MIF binds to a complex of CD74 and CD44, resulting in initiation of a signaling pathway. In the current study, we investigated the role of MIF in B cell survival. We show that in B lymphocytes, MIF initiates a signaling cascade that involves Syk and Akt, leading to NF-kappaB activation, proliferation, and survival in a CD74- and CD44-dependent manner. Thus, MIF regulates the adaptive immune response by maintaining the mature B cell population.     

The developmental outcomes of P0-mediated ARGONAUTE destabilization in tomato

The plant protein ARGONAUTE1 (AGO1) functions in multiple RNA-silencing pathways, including those of microRNAs, key regulators of growth and development. Genetic analysis of ago1 mutants with informative defects has provided valuable insights into AGO1’s biological functions. Tomato encodes two AGO1 homologs (SlAGO1s), but mutants have not been described to date. To analyze SlAGO1s’ involvement in development, we confirmed that both undergo decay in the presence of the Polerovirus silencing suppressor P0 and produce a transgenic responder line (OP:P0HA) that, upon transactivation, expresses P0 C-terminally fused to a hemagglutinin (HA) tag (P0HA) and destabilizes SlAGO1s at the site of expression. By crossing OP:P0HA with a battery of driver lines, constitutive as well as organ- and stage-specific SlAGO1 downregulation was induced in the F1 progeny. Activated plants exhibited various developmental phenotypes that partially overlapped with those of Arabidopsis ago1 mutants. Plants that constitutively expressed P0HA had reduced SlAGO1 levels and increased accumulation of miRNA targets, indicating compromised SlAGO1-mediated silencing. Consistent with this, they exhibited pleiotropic morphological defects and their growth was arrested post-germination. Transactivation of P0HA in young leaf and floral organ primordia dramatically modified corresponding organ morphology, including the radialization of leaflets, petals and anthers, suggesting that SlAGO1s’ activities are required for normal lateral organ development and polarity. Overall, our results suggest that the OP:P0HA responder line can serve as a valuable tool to suppress SlAGO1 silencing pathways in tomato. The suppression of additional SlAGOs by P0HA and its contribution to the observed phenotypes awaits investigation.     

Timing of callase activity and cytoplasmic male sterility in Petunia

A study of callase activity in relation to cytogenetical expressions in cytoplasmic male sterile and male fertile Petunia indicated differential timing of the localized enzyme activity. Enzyme activity was determined by a new test. The possible relations between the mode of action of the extrachromosomal gene, timing of the enzyme activity, and male sterility are discussed.Paper No. 1360-E, 1968 Series of the Volcani Institute of Agricultural Research. Supported in part by grant No. FG-Is-171 of the United States Department of Agriculture, Authorized by U.S. Public Law 480.Deceased.     

The influence of processing corn grain on glucose metabolism in ewes.

Glucose metabolism was studied in ewes fed 800 g chopped alfalfa hay (H) or 400 g alfalfa hay and 400 g corn grain given in whole (HWC), ground (HGC) or extruded (HEC) form. Daily intake of metabolisable energy and crude protein were: 5.8 MJ, 109 g; 9.0 MJ, 84 g; 9.5 MJ, 84 g and 8.5 MJ, 88 g in H, HWC, HGC and HEC, respectively. In situ ruminal degradability ranked whole, ground, and extruded corn in ascending order. Ruminal pH and concentration of acetic acid were lower and of propionic acid higher (P less than 0.05) in HEC than in HGC and HWC groups. Plasma level of glucose (P less than 0.10), insulin (P less than 0.05), and the ratio of insulin to non-esterified fatty acids (NEFA) (P less than 0.01) were higher in HEC than in other groups. Glucose irreversible loss (GILR) and entry rate (GER), recycling (GRec) and reentry (GRee) were determined by double isotope dilution procedure. GER, but not GILR, was higher in HWC than in H and HGC (6.98 mg/min/kg BW0.75 vs 3.97 and 4.24 mg/min/kg BW0.75, respectively; P less than 0.05) and than in HEC (4.84 mg/min/kg BW0.75; P less than 0.10). GRec and GRee were higher in HWC than in the other treatments. Grinding or extruding the grain increased ruminal degradability and decreased glucose entry rate.