IL-6, RANKL, TNF-alpha/IL-1: interrelations in bone resorption pathophysiology

All osteogenic cells (osteoclasts, osteoblasts) contribute individually to bone remodeling. Their cellular interactions control their cellular activities and the bone remodeling intensity. These interactions can be established either through a cell-cell contact, involving molecules of the integrin family, or by the release of many polypeptidic factors and/or their soluble receptor chains. These factors can act directly on osteogenic cells and their precursors to control differentiation, formation and functions (matrix formation, mineralization, resorption...). Here, we present the involvement of three groups of cytokines which seem to be of particular importance in bone physiology: interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) (TNF-alpha)/IL-1, and the more recently known triad osteoprotegerin (OPG)/receptor activator of NF-kappaB (RANK)/RANK ligand (RANKL). The interactions between these three groups are presented within the framework of bone resorption pathophysiology such as tumor associated osteolysis. The central role of the OPG/RANK/RANKL triad is pointed out.     

Nifedipine protects against overproduction of superoxide anion by monocytes from patients with systemic sclerosis

We have reported previously that dihydropyridine-type calcium-channel antagonists (DTCCA) such as nifedipine decrease plasma markers of oxidative stress damage in systemic sclerosis (SSc). To clarify the cellular basis of these beneficial effects, we investigated the effects in vivo and in vitro of nifedipine on superoxide anion (O₂ ^•-) production by peripheral blood monocytes. We compared 10 healthy controls with 12 patients with SSc, first after interruption of treatment with DTCCA and second after 2 weeks of treatment with nifedipine (60 mg/day). O₂ ^•- production by monocytes stimulated with phorbol myristate acetate (PMA) was quantified by the cytochrome c reduction method. We also investigated the effects in vitro of DTCCA on O₂ ^•- production and protein phosphorylation in healthy monocytes and on protein kinase C (PKC) activity using recombinant PKC. After DTCCA had been washed out, monocytes from patients with SSc produced more O₂ ^•- than those from controls. Nifedipine treatment considerably decreased O₂ ^•- production by PMA-stimulated monocytes. Treatment of healthy monocytes with nifedipine in vitro inhibited PMA-induced O₂ ^•- production and protein phosphorylation in a dose-dependent manner. Finally, nifedipine strongly inhibited the activity of recombinant PKC in vitro. Thus, the oxidative stress damage observed in SSc is consistent with O₂ ^•- overproduction by primed monocytes. This was decreased by nifedipine treatment both in vivo and in vitro. This beneficial property of nifedipine seems to be mediated by its cellular action and by the inhibition of PKC activity. This supports the hypothesis that this drug could be useful for the treatment of diseases associated with oxidative stress.     

Visualization of gene expression of prolactin-receptor (PRL-R) by in situ hybridization in reproductive organs of<Emphasis Type="Italic"> Typhlonectes compressicauda</Emphasis>, a gymnophionan amphibian

The expression of the long form of prolactin receptor (PRL-R) mRNAs was studied in reproductive organs from both male and female Typhlonectes compressicauda, an amphibian, by quantitative in situ hybridization. These PRL-R mRNAs were expressed in all the organs studied. In ovarian tissue, mRNAs coding for the long form of PRL-R were strongly expressed in ovaries with compact and vascularized corpora lutea, i.e., during the middle and the end of pregnancy. During the other periods of cycle, sexual rest, vitellogenesis and beginning of pregnancy, expression of these mRNAs was lower than in other periods. In the testis, mRNAs coding for the long form of PRL-R were expressed in germ cells as well as in Leydig and Sertoli cells. In müllerian glands, important variations of expression in these mRNAs have been observed with a large increase during the breeding period and a decrease during sexual rest. Variations of gene expression of the long form of PRL-R for all tissues studied are correlated to synthesis of PRL in the pituitary in both male and female Typhlonectes compressicauda.     

Magnitude and kinetics of rehydration influence the viability of dehydrated E. coli K-12

The influence of rehydration conditions on the recovery of Escherichia coli K-12 was studied. The results showed that the osmotic pressure gradient of rehydration shock realized before plating greatly affected cell viability. When rehydration occurred quickly from an hyperosmotic level of 133 MPa in glycerol solution before slow rehydration by plating on an agar surface to reach initial osmotic pressure (1.4 MPa), bacterial viability was strongly related to the intensity of the hypo-osmotic gradient used. Rehydration to 107 MPa resulted in a survival ratio of 41%, whereas strong rehydration to 1.4 MPa resulted in only 0.7% survival. These studies also demonstrated the influence of the rehydration kinetic on cell recovery. An optimal rehydration rate of 0.136 MPa x s(-1) increased cell recovery by a factor of 40 when compared with the faster and slower rates of 131.6 MPa x s(-1) and 0.006 MPa x s(-1), respectively.     

Changing the conformation state of cytochrome b558 initiates NADPH oxidase activation: MRP8/MRP14 regulation

Phagocyte NADPH oxidase generates O2. for defense mechanisms and cellular signaling. Myeloid-related proteins MRP8 and MRP14 of the S100 family are EF-hand calcium-binding proteins. MRP8 and MRP14 were co-isolated from neutrophils on an anti-p47phox matrix with oxidase cytosolic factors and identified by mass spectrometry. MRP8 and MRP14 are absent from Epstein-Barr virus-immortalized B lymphocytes, and, coincidentally, these cells display weak oxidase activity compared with neutrophils. MRP8/MRP14 that was purified from neutrophils enhanced oxidase turnover of B cells in vitro, suggesting that MRP8/MRP14 is involved in the activation process. This was confirmed ex vivo by co-transfection of Epstein-Barr virus-transformed B lymphocytes with genes encoding MRP8 and MRP14. In a semi-recombinant cell-free assay, recombinant MRP8/MRP14 increased the affinity of p67phox for cytochrome b558 synergistically with p47phox. Moreover, MRP8/MRP14 initiated oxidase activation on its own, through a calcium-dependent specific interaction with cytochrome b558 as shown by atomic force microscopy and a structure-function relationship investigation. The data suggest that the change of conformation in cytochrome b558, which initiates the electron transfer, can be mediated by effectors other than oxidase cytosolic factors p67phox and p47phox. Moreover, MRP8/MRP14 dimer behaves as a positive mediator of phagocyte NADPH oxidase regulation.     

Ovulation rate and distribution in the thoroughbred mare, as determined by ultrasonic scanning: the effect of age

Ovarian activity was monitored in 2181 oestrous cycles from 1136 thoroughbred brood mares to accurately determine overall ovulation rate, the relative distribution of ovulations between left and right ovary, whether mare age had an effect on these parameters and whether ovulation pattern in one cycle affected the pattern within the next. Ultrasonic scanning was used in preference to rectal palpation and slaughterhouse material due to its greater accuracy. Mare's ages ranged from 3 to 22 years. The results obtained indicated a similar incidence of ovulation occurring on the right (49.5% of all ovulations) or left ovary (50.5%). Multiple ovulations (MO) occurred in 22.4% of oestrous cycles. Significantly (P<0.01), more double ovulations (DO) were bilateral (57.2%) than unilateral (42.8%); 20.7% were unilateral right and 22.1% were unilateral left. There were 828 mares grouped into six age groups: A (3-5 years), B (6-8 years), C (9-11 years), D (12-14 years), E (15-18 years), F (18-22 years). The distribution of ovulation between the left and right ovary was not affected by age group, but significant association (P<0.01) was evident between age and MO. Group A had 15% of cycles resulting in MO compared to 19.4, 24.6, 25.8, 28.6 and 35.1% in groups B-F, respectively. A significant (P<0.01) association between MO in successive cycles was also demonstrated, with a greater chance (P<0.05) of successive single ovulations (SO) being on alternate ovaries. There was no significant repeatability of the classification of DO in one cycle compared to the next. We conclude that: (i) the mare is a symmetrical ovulator; (ii) 22.4% of cycles yield MO (ovulation rate 1.23); (iii) this MO incidence increased (P<0.01) with age; (iv) the exhibition of MO in one cycle was linked to an increased probability (P<0.01) of a MO occurring at the next one and (v) SO in one ovary was more likely (P<0.05) to be followed by a SO on the alternate ovary during the next cycle.     

Recessive resistance genes against potyviruses are localized in colinear genomic regions of the tomato ( Lycopersicon spp.) and pepper ( Capsicum spp.) genomes

Resistance against both Potato virus Y (PVY) and Tobacco etch virus (TEV) was identified in the wild tomato relative Lycopersicon hirsutum PI247087. Analysis of the segregation ratio in F(2)/F(3) and BC(1) interspecific progenies indicated that a single recessive gene, or two very tightly linked recessive loci, are involved in resistance to both potyviruses. This locus was named pot-1. Using amplified fragment length polymorphism markers and a set of L. hirsutum introgression lines, pot-1 was mapped to the short arm of tomato chromosome 3, in the vicinity of the recessive py-1 locus for resistance to corky root rot. Because of the occurrence of phenotypically similar genes in pepper ( Capsicum spp.), the comparative genetics of resistance to potyviruses between tomato and pepper was investigated. Unlike most of the comparative genetic studies on resistance genes, pot-1 was tightly flanked by the same restriction fragment length polymorphism (RFLP) markers than the pvr2/pvr5 locus for resistance to PVY and TEV from pepper. These results may indicate that recessive resistance genes against potyviruses evolve less rapidly than the majority of the dominant genes cloned so far, and consequently may belong to a different family of resistance genes.     

Identification and functional analysis of a naturally occurring E89K mutation in the ABCA1 gene of the WHAM chicken

The Wisconsin hypoalpha mutant (WHAM) chicken has a >90% reduction in plasma HDL due to hypercatabolism by the kidney of lipid-poor apoA-I. The WHAM chickens have a recessive white skin phenotype caused by a single-gene mutation that maps to the chicken Z-chromosome. This corresponds to human 9q31.1, a chromosomal segment that contains the ATP-binding cassette protein-1 (ABCA1) gene, which is mutated in Tangier Disease and familial hypoalphalipoproteinemia. Complete sequencing of the WHAM ABCA1 cDNA identified a missense mutation near the N-terminus of the protein (E89K). The substitution of this evolutionary conserved glutamate residue for lysine in the mouse ABCA1 transporter leads to complete loss of function, resulting principally from defective intracellular trafficking and very little ABCA1 reaching the plasma membrane. The WHAM chicken is a naturally occurring animal model for Tangier Disease.