The intensity of the foreign body response to polyether-polyurethane implant in diabetic mice is strain-dependent.

A number of genetic factors have been linked to the development of diabetes, a condition that often requires implantable devices such as glucose sensors. In normoglycaemic individuals, this procedure induces a foreign body reaction (FBR) that is detrimental to bioimplant functionality. However, the influence of the genetic background on this reaction in diabetes has not been investigated. We examined the components of FBR (capsule thickness, collagen deposition, mast cell and foreign body giant cell number) in subcutaneous implants of polyether polyurethane (SIPP) in streptozotocin (STZ)-induced diabetes in Swiss, C57BL/6 and Balb/c mice. The fasting blood glucose levels before STZ injections were 133.5 ± 5.1 mg/dL, after the treatment increased 68.4% in Swiss mice, 62.4% in C57BL/6 and 30.9% in Balb/c mice. All FBR features were higher in implants of Swiss and C57BL/6 mice compared with those in implants of Balb/c. Likewise, the apoptotic index was higher in implants of diabetic Swiss and C57BL/6 mice whose glycaemic levels were the highest. Our findings show an association between the severity of hyperglycaemic levels and the intensity of the FBR to SIPP. These important strain-related differences in susceptibility to diabetes and the intensity of the FBR must be considered in management using implantable devices in diabetic individuals.

Long-term treatment with kefir probiotics ameliorates cardiac function in spontaneously hypertensive rats.

This work evaluated the effects of long-term kefir treatment in cardiac function (cardiac contractility and calcium-handling proteins) and the central nervous system (CNS) control of the sympathetic signaling in spontaneously hypertensive rats (SHR). Male normotensive rats [Wistar Kyoto rats (WKYs)] and SHRs were divided into three groups: WKYs and SHRs treated with vehicle, and SHRs treated with milk fermented by the grains of kefir (5%; SHR-Kefir; oral gavage, 0.3 ml/100 g daily/9 weeks). At the end of treatment, mean arterial pressure (MAP) and heart rate (HR) were measured by direct arterial catheterization. Hemodynamic parameters (left ventricular systolic pressure, left ventricular isovolumetric relaxation time constant, maximal and minimal pressure decay) were acquired through a left ventricular catheter implantation. Left ventricle protein expressions of phospholamban (PLB), its phosphorylated form (p-PLB) and sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) were determined by Western blot. Tyrosine hydroxylase (TH) protein expression was evaluated via immunofluorescence within the paraventricular nucleus (PVN) of the hypothalamus and the rostral ventrolateral medulla (RVLM). SHR-Kefir group presented lower MAP and HR compared to SHRs. Kefir treatment ameliorated cardiac hypertrophy and promoted reduced expression of PLB, p-PLB and SERCA2a contractile proteins. Within the PVN and RVML, TH protein overexpression observed in SHRs was reduced by probiotic treatment. In addition, kefir improved cardiac hemodynamic parameters in SHR-treated animals. Altogether, the data show that long-term kefir treatment reduced blood pressure by mechanisms involving reduction of cardiac hypertrophy, improvement of cardiac contractility and calcium-handling proteins, and reduction in the CNS regulation of the sympathetic activity.

Aliskiren and l-arginine treatments restore depressed baroreflex sensitivity and decrease oxidative stress in renovascular hypertension rats.

Renovascular hypertension is characterized by increased angiotensin II and oxidative stress, and by endothelial dysfunction. The purpose of this study was to test whether the administration of aliskiren (ALSK) and l-arginine (l-ARG) would restore impaired baroreflex sensitivity and reduce oxidative stress in a rat renovascular hypertension model. Hypertension was induced by clipping the left renal artery, and the following five groups were created: SHAM; two-kidney, 1-clip (2K1C); 2K1C plus ALSK (ALSK); 2K1C plus l-ARG (l-ARG); and 2K1C plus ALSK+l-ARG (ALSK+l-ARG). After 21 days of treatment, only the ALSK+l-ARG group was effective in normalizing the arterial pressure (108.8±2.8 mm Hg). The l-ARG and ALSK+l-ARG groups did not show hypertrophy of the left ventricle. All the treatments restored the depressed baroreflex sensitivity to values found in the SHAM group. Acute administration of TEMPOL restored the depressed baroreflex sensitivity in the 2K1C group to values that resembled those presented by the other groups. All treatments were effective for an increase in the antioxidant pathway and reduction in the oxidative pathway. In conclusion, the treatment with ALSK or l-ARG reduced oxidative stress and restored reduced baroreflex sensitivity in renovascular hypertension. In addition, the treatments were able to normalize blood pressure and reverse left ventricular hypertrophy when used in combination.

Natriuretic peptide clearance receptor ligand (C-ANP4-23 ) attenuates angiogenesis in a murine sponge implant model.

Natriuretic peptide receptor-C activation by the synthetic ligand C-ANP-4-23, a specific agonist for this receptor, has been shown to inhibit key events of the angiogenic cascade, such as migration, proliferation and vascular endothelial growth factor (VEGF) production. In the present study we investigated whether C-ANP4-23 could also inhibit angiogenesis in the sponge model in vivo. To this end, we evaluated the effects of C-ANP4-23 on inflammatory and angiogenic components of the fibrovascular tissue induced by polyether polyurethane sponge implants in mice. Measurements of the haemoglobin content (µg/mg wet tissue) and blood flow (laser Doppler perfusion imaging) of the implants, used as an index of vascularization, revealed that single (200 ng) or multiple (200 ng/day, 5 days) doses of C-ANP4-23 reduced angiogenesis in the implants relative to the phosphate-buffered saline-treated group. The peptide exerted an inhibitory effect on nitric oxide production (nitrite levels) and had a dual effect on VEGF levels, depending on the number of doses (i.e. stimulation at 4 days after one dose; inhibition at 7 days after five doses). Histological analysis corroborated the biochemical and functional parameters indicative of inhibition of neovascularization (decreased vessel number) by C-ANP4-23 . The peptide failed to modulate inflammation in our system. The inhibitory effect of C-ANP4-23 on the angiogenic component of the fibrovascular tissue induced by the synthetic matrix extends the range of the its actions and may indicate its therapeutic potential in controlling angiogenesis in fibroproliferative diseases.