Effects of polyunsaturated fatty acids (PUFAs) in the treatment of experimental chronic renal failure

Purpose

A diet with polyunsaturated fatty acid (PUFA) supplementation has been reported to reduce renal and cardiac diseases. This study sought to elucidate whether PUFAs derived from plant or marine oils could have beneficial effects on the progression of experimental chronic renal failure (CRF).

Methods

Experimental CRF was achieved by a 5/6 nephrectomy model. Male Wistar rats were divided into groups and given daily supplements of fish oil (group FO), flaxseed oil (group FXO), or soybean oil (control?Cgroup SO) for 30?days. Serum creatinine (sCr), 24-h proteinuria, total cholesterol, triglycerides, and creatinine clearance (CLcr) were measured at day 0 and 30?days after surgery when the rats were euthanized for histological analysis of the remnant kidney.

Results

After 30?days, we observed lower levels of sCr in the groups supplemented with PUFA when compared with the control group (FO: 0.92?±?0.13; FXO: 1.06?±?0.28; SO: 1.32?±?0.47?mg/dL) and significantly slower variations of sCr (??sCr) in the groups treated with PUFAs (FO?=?0.35?±?0.16; FXO?=?0.47?±?0.31; OS?=?0.72?±?0.43; mg/dL, P?=?0.041). Similarly, the CLcr of both of the groups that received PUFAs was significantly slower than the rats in the control group (FO: 0.45?±?0.15; FXO: 0.60?±?0.09; SO: 0.28?±?0.06?mL/min/day; P?=?0.01). The rats that received PUFA supplements also presented significantly less histological lesions compared with the control group.

Conclusions

These results suggest a beneficial effect of dietary supplementation with flaxseed or fish oil in rats with CRF.     

Regulation of p53 is critical for vertebrate limb regeneration

Extensive regeneration of the vertebrate body plan is found in salamander and fish species. In these organisms, regeneration takes place through reprogramming of differentiated cells, proliferation, and subsequent redifferentiation of adult tissues. Such plasticity is rarely found in adult mammalian tissues, and this has been proposed as the basis of their inability to regenerate complex structures. Despite their importance, the mechanisms underlying the regulation of the differentiated state during regeneration remain unclear. Here, we analyzed the role of the tumor-suppressor p53 during salamander limb regeneration. The activity of p53 initially decreases and then returns to baseline. Its down-regulation is required for formation of the blastema, and its up-regulation is necessary for the redifferentiation phase. Importantly, we show that a decrease in the level of p53 activity is critical for cell cycle reentry of postmitotic, differentiated cells, whereas an increase is required for muscle differentiation. In addition, we have uncovered a potential mechanism for the regulation of p53 during limb regeneration, based on its competitive inhibition by ΔNp73. Our results suggest that the regulation of p53 activity is a pivotal mechanism that controls the plasticity of the differentiated state during regeneration.Unlike mammals, which exhibit limited regenerative abilities, the urodele amphibians—or salamanders—are capable of regenerating an extraordinary range of body structures, including ocular tissues, tail, sections of the heart, parts of the nervous system, and entire limbs (1). In salamanders, such as the newt and axolotl, limb regeneration depends on the formation of a blastema, a mound of progenitor cells of restricted potential that arises after amputation (2–4). Following a period of proliferation, blastema cells redifferentiate and restore the structures of the limb.Extensive evidence indicates that limb regeneration depends on reprogramming of cells in mature limb tissues. Upon amputation, muscle, cartilage, and connective tissue cells underneath the injury site lose their differentiated characteristics and re-enter the cell cycle to give rise to the blastema (5–8). This mechanism has also been observed during zebrafish heart and fin regeneration (9, 10). In contrast, reversals of the differentiated state are rarely observed in mammalian tissues, which led to the suggestion that inability to undergo dedifferentiation could contribute to the failure of regeneration in mammals (11). Despite their significance, the mechanisms underlying regulation of the differentiated state during vertebrate regeneration remain poorly understood.Recently, the tumor suppressor p53, whose best-characterized functions are in the maintenance of genome stability (12), has been implicated in the suppression of artificial cell reprogramming to pluripotency (13–17) and the promotion of differentiation pathways in mammals (18). In addition, it has been observed that inhibiting p53 disrupts limb regrowth in salamanders (19), although its role in this context has remained unknown. It is possible that p53 could play a role in the regulation of dedifferentiation and redifferentiation events intrinsic to vertebrate regeneration. Our results demonstrate that the regulation of p53 activity is critical for limb regeneration by controlling key cell fate decisions throughout this process.     

Retinal axon regeneration in the lizard Gallotia galloti in the presence of CNS myelin and oligodendrocytes

Retinal ganglion cell (RGC) axons in lizards (reptiles) were found to regenerate after optic nerve injury. To determine whether regeneration occurs because the visual pathway has growth-supporting glia cells or whether RGC axons regrow despite the presence of neurite growth-inhibitory components, the substrate properties of lizard optic nerve myelin and of oligodendrocytes were analyzed in vitro, using rat dorsal root ganglion (DRG) neurons. In addition, the response of lizard RGC axons upon contact with rat and reptilian oligodendrocytes or with myelin proteins from the mammalian central nervous system (CNS) was monitored. Lizard optic nerve myelin inhibited extension of rat DRG neurites, and lizard oligodendrocytes elicited DRG growth cone collapse. Both effects were partially reversed by antibody IN-1 against mammalian 35/250 kD neurite growth inhibitors, and IN-1 stained myelinated fiber tracts in the lizard CNS. However, lizard RGC growth cones grew freely across oligodendrocytes from the rat and the reptilian CNS. Mammalian CNS myelin proteins reconstituted into liposomes and added to elongating lizard RGC axons caused at most a transient collapse reaction. Growth cones always recovered within an hour and regrew. Thus, lizard CNS myelin and oligodendrocytes possess nonpermissive substrate properties for DRG neurons—like corresponding structures and cells in the mammalian CNS, including mammalian-like neurite growth inhibitors. Lizard RGC axons, however, appear to be far less sensitive to these inhibitory substrate components and therefore may be able to regenerate through the visual pathway despite the presence of myelin and oligodendrocytes that block growth of DRG neurites. GLIA 22:61–74, 1998. © 1998 Wiley-Liss, Inc.     

Nogo‐A does not inhibit retinal axon regeneration in the lizard Gallotia galloti

The myelin‐associated protein Nogo‐A contributes to the failure of axon regeneration in the mammalian central nervous system (CNS). Inhibition of axon growth by Nogo‐A is mediated by the Nogo‐66 receptor (NgR). Nonmammalian vertebrates, however, are capable of spontaneous CNS axon regeneration, and we have shown that retinal ganglion cell (RGC) axons regenerate in the lizard Gallotia galloti. Using immunohistochemistry, we observed spatiotemporal regulation of Nogo‐A and NgR in cell bodies and axons of RGCs during ontogeny. In the adult lizard, expression of Nogo‐A was associated with myelinated axon tracts and upregulated in oligodendrocytes during RGC axon regeneration. NgR became upregulated in RGCs following optic nerve injury. In in vitro studies, Nogo‐A‐Fc failed to inhibit growth of lizard RGC axons. The inhibitor of protein kinase A (pkA) activity KT5720 blocked growth of lizard RGC axons on substrates of Nogo‐A‐Fc, but not laminin. On patterned substrates of Nogo‐A‐Fc, KT5720 caused restriction of axon growth to areas devoid of Nogo‐A‐Fc. Levels of cyclic adenosine monophosphate (cAMP) were elevated over sustained periods in lizard RGCs following optic nerve lesion. We conclude that Nogo‐A and NgR are expressed in a mammalian‐like pattern and are upregulated following optic nerve injury, but the presence of Nogo‐A does not inhibit RGC axon regeneration in the lizard visual pathway. The results of outgrowth assays suggest that outgrowth‐promoting substrates and activation of the cAMP/pkA signaling pathway play a key role in spontaneous lizard retinal axon regeneration in the presence of Nogo‐A. Restriction of axon growth by patterned Nogo‐A‐Fc substrates suggests that Nogo‐A may contribute to axon guidance in the lizard visual system. J. Comp. Neurol. 525:936–954, 2017. © 2016 Wiley Periodicals, Inc.     

Overall breast density in MR mammography: diagnostic and therapeutic implications in breast cancer

The objective of this study was to assess the efficacy of MR mammography (MRM) in evaluating breast cancer extent in women with fatty or dense breasts, and its contribution to the therapeutic approach. The authors reviewed 97 carcinomas detected in 93 women (both symptomatic and from screening) that were classified in two groups according to breast density pattern. Mammography, ultrasound (US), and MRM were performed to evaluate size, extension of the in situ component, presence of multifocal/multicentric disease, and contralateral involvement. Results obtained on mammography plus US were balanced against MRM, considering pathologic analysis as the gold standard. For fatty breasts (n=47), exact measurement was found on mammography plus US and on MRM alone in 70%, underestimation on mammography plus US 23.5% and on MRM 11% (P=0.005). For dense breasts (n=50), exact measurement was found on mammography plus US in 40% and on MRM alone 68%, underestimation on mammography plus US 52% and on MRM 10% (P=0.005). Overall, good correlation (R>0.71) was found between pathologic and clinical size with all imaging methods; nevertheless, when evaluating multifocal/multicentric disease, a poor correlation was observed between histologic assessment and mammography plus US (R=0.52), but it was excellent with regard to MRM (R=0.99). In fatty breasts, the combination of mammography and US allows for a precise assessment of tumoral extension. However, these results show that in dense breasts, MRM is superior to mammography plus US, suggesting that its systematic use in this group of patients is justifiable.     

Regrowth of transected retinal ganglion cell axons despite persistent astrogliosis in the lizard (Gallotia galloti)

We analysed the astroglia response that is concurrent with spontaneous axonal regrowth after optic nerve (ON) transection in the lizard Gallotia galloti. At different post-lesional time points (0.5, 1, 3, 6, 9 and 12 months) we used conventional electron microscopy and specific markers for astrocytes [glial fibrillary acidic protein (GFAP), vimentin (Vim), sex-determining region Y-box-9 (Sox9), paired box-2 (Pax2)¸ cluster differentiation-44 (CD44)] and for proliferating cells (PCNA). The experimental retina showed a limited glial response since the increase of gliofilaments was not significant when compared with controls, and proliferating cells were undetectable. Conversely, PCNA⁺ cells populated the regenerating ON, optic tract (OTr) and ventricular wall of both the hypothalamus and optic tectum (OT). Subpopulations of these PCNA⁺ cells were identified as GFAP⁺ and Vim⁺ reactive astrocytes and radial glia. Reactive astrocytes up-regulated Vim at 1 month post-lesion, and both Vim and GFAP at 12 months post-lesion in the ON-OTr, indicating long-term astrogliosis. They also expressed Pax2, Sox9 and CD44 in the ON, and Sox9 in the OTr. Concomitantly, persistent tissue cavities and disorganised regrowing fibre bundles reaching the OT were observed. Our ultrastructural data confirm abundant gliofilaments in reactive astrocytes joined by desmosomes. Remarkably, they also accumulated myelin debris and lipid droplets until late stages, indicating their participation in myelin removal. These data suggest that persistent mammalian-like astrogliosis in the adult lizard ON contributes to a permissive structural scaffold for long-term axonal regeneration and provides a useful model to study the molecular mechanisms involved in these beneficial neuron–glia interactions.     

Expression of GM1, a marker of lipid rafts, defines two subsets of human monocytes with differential endocytic capacity and lipopolysaccharide responsiveness

Monocytes constitute 5-10% of total human peripheral blood leucocytes and remain in circulation for several days before replenishing the tissue macrophage populations. Monocytes display heterogeneity in size, granularity and nuclear morphology, and in the expression of cell membrane molecules, such as CD14, CD16, CD32, CD64, major histocompatibility complex class II, CCR2, CCR5, among others. This has led to the suggestion that individual monocyte/macrophage populations have specialized functions within their microenvironments. This study provides evidence for the occurrence of two peripheral blood monocyte subpopulations on the basis of their differential expression of GM1, a sphingolipid found mostly in lipid rafts, a CD14(+) GM1(low) population and a CD14(+) GM1(high) population comprising about 97.5% and 2.5% of total CD14(+) cells, respectively. GM1 expression correlates with functional differences in terms of endocytic activity, susceptibility to mycobacterial infection, and response to lipopolysaccharide (LPS) (modulation of Toll-like receptor-4 expression). CD14(+) GM1(low) cells proved to be less endocytic and more responsive to LPS, whereas CD14(+) GM1(high) cells are more endocytic and less responsive to LPS. In addition, during monocyte to macrophage differentiation in vitro, the percentage of CD14(+) GM1(high) cells increases from about 2.5% at day 1 to more than 50% at day 7 of culture. These results suggest that GM1(low) and GM1(high) monocytes in peripheral blood, represent either different stages of maturation or different subsets with specialized activities. The expression of CD16 on GM1(high) favours the first possibility and, on the other hand that up-regulation of GM1 expression and probably lipid rafts function is involved in the monocyte to macrophage differentiation process.     

Congenital heart defects and chromosomal anomalies including 22q11 microdeletion (CATCH 22).

OBJECTIVE: To analyze the frequency of chromosomal anomalies or 22q11 microdeletion in patients with congenital heart defects and other congenital anomalies; to describe the clinical phenotype of children with the 22q11 microdeletion and with chromosomal anomalies; to evaluate patients' clinical evolution; and to provide genetic counseling for families. METHODS: The study included 46 patients with congenital heart defects and other anomalies and patients with a phenotype consistent with 22q11 microdeletion observed between 1999 and 2001. Confirmation of the heart defect was accomplished through echocardiography, magnetic resonance angiography or cardiac catheterization. Karyotyping with high resolution banding and detection of 22q11 microdeletion with FISH techniques were performed. We excluded patients with trisomy 21, 13 and 18, 45,X and deletion of 7q11.23. Patients with 22q11 microdeletion underwent immunology studies and evaluation of parathyroid function. Clinical evolution was evaluated. Chromosome and FISH studies were performed on parents of affected children (25 couples). RESULTS: Forty-six children were included, of whom twelve (26.1%) had chromosomal anomalies (group A), fourteen (30.4%) had 22q11 microdeletion (group B) and the remaining twenty (43.5%) had normal karyotype and negative FISH studies (group C). In group A septal heart defects predominated. This group had significant morbidity, with surgical correction in three patients, early development of pulmonary hypertension, failure to thrive and serious neurological problems. Two patients died. In group B conotruncal heart defects (7/14) and ventricular septal defects (5/14, two associated with cervical aortic arch) predominated. The most significant morbidity was related to cardiac pathology, with surgical correction in seven cases (50%). Immune function defects and parathyroid function problems were mild, requiring no therapeutic measures. One patient died. CONCLUSION: In the presence of heart defects associated with other congenital anomalies, karyotyping is mandatory and if clinical features are compatible, 22q11 microdeletion should be specifically sought with FISH techniques. Detection of chromosomal anomalies has a significant impact on prognosis and follow-up of patients, as well as on genetic counseling of families.