Isolation and characterization of a mRNA encoding a novel insulin receptor (IR) subtype, IR2, from rainbow trout (Oncorhynchus mykiss) and patterns of expression of the four IR subtypes, IR1-IR4, in tissues and during embryonic development

Insulin (INS) plays a critical role in the growth, development, and metabolism of vertebrates. In this study, a cDNA encoding a novel insulin receptor (IR) subtype was isolated, cloned, and sequenced from the liver of rainbow trout. A 1525-bp cDNA encoding a partial amino acid sequence of the β-subunit including the transmembrane domain, the tyrosine kinase domain, and the 3′ untranslated region (UTR) was obtained and designated IR2 based on comparison with known IR subtypes, including the three previously reported IR subtypes of trout. Trout IR2 shares 90.0%, 82.8%, and 84.3% nucleotide identity with previously characterized trout IR1, IR3 and IR4, respectively. Quantitative real-time PCR revealed that the four IR mRNAs were differentially expressed, both in terms of distribution among tissues as well as in terms of abundance within selected tissues of juvenile trout. IR1 mRNA was most abundant in spleen, liver, kidney, and muscle (white, red and cardiac), but least abundant in adipose. IR3 mRNA was most abundant in liver, spleen, kidney, and pancreas; in other tissues, levels of IR3 mRNA were uniformly abundant. By contrast, levels of IR2 and IR4 mRNA were uniformly abundant in most tissues, except in spleen where levels of IR4 were significantly lower. All IR subtypes were detected over the course of embryonic development. In head and tail regions, levels of IR2 and IR3 mRNA declined from pre-hatch (29 days post-fertilization, dpf) to post-hatch (68-90 dpf), whereas levels of IR1 and IR4 remained relatively unchanged. These findings contribute to our understanding of the evolution, distribution, and function of insulin receptors.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Inflammation, ageing and cancer

Cancer is generally recognized as an age-related disease. In fact, incidence and mortality rates of most human cancers increase consistently with age up to 90 years, but they plateau and decline thereafter. A low-grade systemic inflammation characterizes ageing and this pro-inflammatory status underlies biological mechanisms responsible for age-related inflammatory diseases. On the other hand, clinical and epidemiological studies show a strong association between chronic infection, inflammation and cancer and indicate that even in tumours not directly linked to pathogens, the microenvironment is characterized by the presence of a smouldering inflammation, fuelled primarily by stromal leukocytes. In this review, we have briefly mentioned inflammatory mediators involved in cancer although we decided to choose the ones which show a strict association with ageing and longevity. Inflammation is necessary to manage with damaging agents and is crucial for survival. But, in our opinion, the pro-inflammatory status of ageing might be one of the mechanisms which relate cancer to ageing. The most appropriate inflammatory genes have been selected to survive and to reproduce. Paradoxically, inflammatory age-related diseases (including cancer) are the marks of the same evolutionistic trait. Centenarians are characterized by a higher frequency of genetic markers associated with better control of inflammation. The reduced capacity of centenarians to mount inflammatory responses appears to exert a protective effect towards the development of those age-related pathologies having a strong inflammatory pathogenetic component, including cancer. All in all, centenarians seem to carry a genetic background with a peculiar resistance to cancer which is also an anti-inflammatory profile.     

Functional evaluation of collagen fiber scaffolds for ACL reconstruction: cyclic loading in proteolytic enzyme solutions

The mechanical properties of anterior cruciate ligament (ACL) reconstruction scaffolds were evaluated after exposure to functional challenges in vitro: cyclic loading combined with various proteolytic enzymes. Scaffolds were prepared from collagen fibers that were uncrosslinked (UNXL), crosslinked with ultraviolet irradiation (UV), or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC; 10 or 25 mM). Structural properties of scaffolds were determined following 1-h exposure to saline, trypsin, or bacterial collagenase, with and without simultaneous cyclic tensile loading (0 to 50 g; 0.5 Hz) in vitro. The breaking load and stiffness of UNXL and UV crosslinked scaffolds were significantly reduced by exposure to either trypsin or collagenase. Cyclic loads interacted synergistically with enzymes, rendering UNXL scaffolds untestable and further decreasing the breaking load of UV crosslinked scaffolds by approximately 35%. In contrast, the breaking load and stiffness of EDC crosslinked scaffolds, which were greater than those of UNXL or UV crosslinked scaffolds, were virtually unaffected by the same load and enzyme treatments. These results suggest that EDC is more effective than UV for crosslinking and stabilizing load-bearing collagen fiber ACL reconstruction scaffolds. Application of cyclic loads and enzymes may lead to development of physiologically relevant in vitro test methods for load-bearing scaffolds.     

IL-15 in human visceral leishmaniasis caused by Leishmania infantum

Interleukin (IL)-15 is a recently discovered cytokine with the ability to stimulate the proliferation activity of Th1 and/or Th2 lymphocytes. Here, we investigated the involvement of IL-15 in the immune response to Leishmania infantum infection by studying patients with visceral leishmaniasis (VL). We found that IL-15 is produced by leishmanial antigen (LAg)-stimulated peripheral blood mononuclear cells (PBMC) from active VL patients at a significantly higher level than those produced by cells from healed VL subjects or healthy controls. A significant increase in IL-15 serum blood levels was also observed in acute VL patients compared with healed ones. Furthermore, recombinant IL-15 had an appreciable effect in vitro in reducing IL-4 and increasing the production of IL-12 in response to LAg, but it was ineffective in altering the production of interferon-gamma (IFN-gamma). The production of endogenous IL-15 in acute VL patients appeared to be insufficient to activate both IFN-gamma and IL-12, as attested by the absence of modification of these two cytokines by neutralization experiments in the presence of anti-IL-15 monoclonal antibodies (MoAB). On the contrary, the neutralization of IL-15 increased IL-4 production. Together, these results indicate that endogenous IL-15 plays a role in the suppression of Th2-type cytokines, even though it does not enhance the production of Th1 cytokines in acute VL patients. Since IL-15, in the presence of anti-IL-4 MoAb, caused a further increase in IL-12 production and led to a significant production of IFN-gamma, one of its indirect effects on Th1 cell activation could be due to the latter's effect on Th2 cytokines such as IL-4. Therefore, our observations indicate that there is a potential for IL-15 to augment the T-cell response to human intracellular pathogens.     

Low-molecular weight heparin induces in vitro trophoblast invasiveness: role of matrix metalloproteinases and tissue inhibitors

Heparin is used widely for the prevention of pregnancy loss in pregnant women with thrombophilia. However, it is still unknown if heparin may be able to affect trophoblast functions. Therefore, we investigated the hypothesis that low-molecular weight heparin (LMWH) might regulate in vitro trophoblast invasiveness and placental production of matrix metalloproteinases (MMPs) and tissue inhibitors (TIMPs). In the first-trimester placental tissue, the MMP-9 expression was observed in both villous and extravillous cytotrophoblast cells, and MMP-2 mainly in villous cytotrophoblast. In human choriocarcinoma cells (JAR), MMP-2 was the dominant form. Heparin significantly enhanced both pro-MMPs and the active forms, and increased Matrigel invasiveness of extravillous trophoblast and choriocarcinoma cells. In choriocarcinoma cells the heparin effect was also indirect, inducing a significant decrease in TIMP-1 and TIMP-2 protein expressions and mRNAs. The present data suggest that the increase in trophoblast invasion by heparin is due to a specific protein playing a role in placental invasion. These observations may help in understanding the effects of heparin treatment during pregnancy.     

Cytokine production pathway in the elderly

It is well known that aging is associated with various alterations in lymphoid cell functions, particularly with a progressive decline in immune responsiveness to exogenous antigens and increasing incidence of autoimmune phenomena. Many studies have been focused on the mechanisms of the immunologic features of aging. This review describes our results of studies performed to determine the influence of age on the capacity to produce interleukin-2 (IL-2), interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6) and tumor necrosis factor (TNF). Mitogen-stimulated cultures of mononuclear cells (MNC) from human beings were assessed for cytokine-producing capacity. A significant decrease in IFN-γ and IL-2 production by MNC cultures from elderly individuals was observed. No significant difference was instead observed between cultures from elderly individuals and those from young ones as regards TNF-α, IL-4 and IL-6 production. Mitogen or antigen-stimulated cultures of MNC from aged mice also displayed a significant decrease in IFN-γ and IL-2 production as well as TNF-β. Instead IL-4 and IL-5 production significantly increased in these cultures. We suggest that this imbalanced cytokine production may well account for the pattern of immune response which may be observed in the elderly, i.e. a normal or increased humoral response (including autoimmune responses) in face of a low T cell immune responsiveness.     

Biomechanical analysis of a chondrocyte-based repair model of articular cartilage.

The objective of this study was to evaluate the biomechanical properties of newly formed cartilaginous tissue synthesized from isolated chondrocytes. Cartilage from articular joints of lambs was either digested in collagenase to isolated chondrocytes or cut into discs that were devitalized by multiple freeze-thaw cycles. Isolated cells were incubated in suspension culture in the presence of devitalized cartilage matrix for 3 weeks. Multiple chondrocyte/matrix constructs were assembled with fibrin glue and implanted subcutaneously in nude mice for up to 6 weeks. Testing methods were devised to quantify integration of cartilage pieces and mechanical properties of constructs. These studies showed monotonic increase with time in tensile strength, fracture strain, fracture energy, and tensile modulus to values 5-10% of normal articular cartilage by 6 weeks in vivo. Histological analysis indicated that chondrocytes grown on dead cartilage matrix produced new matrix that integrated individual cartilage pieces with mechanically functional tissue.